Metalloid

Elements recognized as metalloids

	13	14	15	16	17
2	B Boron	C Carbon	N Nitrogen	O Oxygen	F Fluorine
3	Al Aluminium	Si Silicon	P Phosphorus	S Sulfur	Cl Chlorine
4	Ga Gallium	Ge Germanium	As Arsenic	Se Selenium	Br Bromine
5	In Indium	Sn Tin	Sb Antimony	Te Tellurium	I Iodine
6	Tl Thallium	Pb Lead	Bi Bismuth	Po Polonium	At Astatine
Commonly recognized (86–99%): B, Si, Ge, As, Sb, Te   Irregularly recognized (40–49%): Po, At   Less commonly recognized (24%): Se   Rarely recognized (8–10%): C, Al   (All other elements cited in less than 6% of sources)   Arbitrary metal-nonmetal dividing line: between Be and B, Al and Si, Ge and As, Sb and Te, Po and At
Recognition status, as metalloids, of some elements in the p-block of the periodic table. Percentages are median appearance frequencies in the lists of metalloids. The staircase-shaped line is a typical example of the arbitrary metal–nonmetal dividing line found on some periodic tables.

A metalloid is a chemical element that has properties in between those of metals and nonmetals. There is no standard definition of a metalloid, nor is there agreement as to which elements are appropriately classified as such. Despite this lack of specificity the term remains in use in chemistry literature.

The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. Less commonly recognised metalloids include carbon, aluminium, selenium, polonium and astatine. On a standard periodic table all of these elements can be found in a diagonal region of the p-block, with its main axis anchored by boron at one end and astatine at the other. Some periodic tables include a dividing line between metals and nonmetals and it is generally the elements adjacent to this line or, less often, one or more of the elements adjacent to those elements, which are identified as metalloids.

Metalloids usually have a metallic appearance but they are brittle and only fair conductors of electricity; chemically, they mostly behave as (weak) nonmetals. They can form alloys with metals. Most of the other physical and chemical properties of metalloids are intermediate in nature.

Metalloids are too brittle to have any structural uses. They and their compounds are used in alloys, biological agents, flame retardants, glasses, optical storage, semiconductors and electronics. The electrical properties of silicon and germanium enabled the establishment of the semiconductor industry in the 1950s and the development of solid-state electronics from the early 1960s.

The term metalloid originally referred to nonmetals. Its more recent meaning, as a category of elements with intermediate or hybrid properties, became widespread in 1940–1960. Metalloids are sometimes called semimetals, a practice that has been discouraged; the term semimetal has a different meaning in physics, one that more specifically refers to the electronic band structure of a substance rather than the overall classification of a chemical element.

Definition

Metalloids are usually regarded as a third category of chemical elements occupying a fuzzy 'buffer zone' between metals and nonmetals. There is no universally agreed, rigorous definition of a metalloid. The feasibility of establishing a specific definition has been questioned; anomalies can be found in several such attempted constructs. Classifying an element as a metalloid has been described as 'arbitrary'.

Generic

A metalloid is an element with properties that are in between or a mixture of those of metals and nonmetals, and that is considered to be hard to classify as either a metal or a nonmetal. This is a generic definition that draws on metalloid attributes consistently cited in the literature. Difficulty of categorisation is a key attribute. Although most other elements have a mixture of metallic and nonmetallic properties, they can be classified according to which set of properties is more pronounced. Only the elements at or near the margins, ordinarily those regarded as lacking a sufficiently clear preponderance of either metallic or nonmetallic properties, are classified as metalloids.

Boron, silicon, germanium, arsenic, antimony and tellurium are commonly recognised as metalloids. Depending on the author, one or more from selenium, polonium or astatine are sometimes added to the list. Boron is sometimes excluded, by itself or with silicon. Tellurium is sometimes not regarded as a metalloid. The inclusion of antimony, polonium and astatine as metalloids has also been questioned.

Other elements are occasionally classified as metalloids. These elements include hydrogen, beryllium, nitrogen, phosphorus, sulfur, zinc, gallium, tin, iodine, lead, bismuth and radon. The term metalloid has also been used for elements that exhibit metallic lustre and electrical conductivity, and that are amphoteric; such as arsenic, antimony, vanadium, chromium, molybdenum, tungsten, tin, lead and aluminium. The poor metals, and nonmetals (such as carbon or nitrogen) that can form alloys with metals or modify their properties have also occasionally been considered as metalloids.

Specific

	Element	IE	EN	Band structure
	Boron	191	2.04	semiconductor
	Silicon	187	1.90	semiconductor
	Germanium	182	2.01	semiconductor
	Arsenic	225	2.18	semimetal
	Antimony	198	2.05	semimetal
	Tellurium	207	2.10	semiconductor
	average	198	2.05
	The elements commonly recognised as metalloids, and their ionization energies (kcal/mol); electronegativities (revised Pauling scale); and electronic band structures (most thermodynamically stable forms under ambient conditions).

Metalloids tend to be characterised in terms of generalities or a few broadly indicative physical or chemical properties. A single quantitative criterion, such as electronegativity is sometimes used. In contrast, Jones (writing on the role of classification in science) observed that, 'Classes are usually defined by more than two attributes.'

Masterton and Slowinski offered a more specific treatment. They wrote that metalloids have ionization energies around 200 kcal/mol, and electronegativity values close to 2.0. They also said that metalloids are typically semiconductors, though antimony and arsenic (semimetals in the physics sense) have electrical conductivities that approach those of metals. Their description, using these three properties, includes the six elements commonly recognised as metalloids (see table, this section). Selenium and polonium are probably excluded from this scheme; astatine may or may not be included.

The commonly recognised metalloids can also be quantitatively described as having packing efficiencies between 34% and 41% and Goldhammer-Herzfeld criterion metallization ratios between ~0.85 and 1.1; average 1.0. The packing efficiency of boron is 38%; silicon and germanium 34; arsenic 38.5; antimony 41; and tellurium 36.4. These values are lower than in most metals (80% of which have a packing efficiency of at least 68%) but higher than those of elements usually classified as nonmetals. Packing efficiencies for nonmetals are: graphite 17%, sulfur 19.2, iodine 23.9, selenium 24.2, and black phosphorus 28.5. The Goldhammer-Herzfeld criterion ratio values of the recognised metalloids are lower than those of representative and transition metals and higher than those of nonmetals.

Periodic table territory

Location

Template:Periodic table (metalloid border) Metalloids lie on either side of the dividing line between metals and nonmetals. This can be found, in varying configurations, on some periodic tables. Elements to the lower left of the line generally display increasing metallic behaviour; elements to the upper right display increasing nonmetallic behaviour. When presented as a regular stairstep, elements with the highest critical temperature for their groups (Li, Be, Al, Ge, Sb, Po) lie just below the line.

The diagonal positioning of the metalloids represents an exception to the observation that elements with similar properties tend to occur in vertical groups. Going along a period, the nuclear charge increases with atomic number as there is as an increase in electrons. The additional 'pull' on outer electrons with increasing nuclear charge generally outweighs the screening efficacy of having more electrons. With some irregularities, atoms therefore become smaller, ionization energy increases, and there is a gradual change in character, across a period, from strongly metallic, to weakly metallic, to weakly nonmetallic, to strongly nonmetallic elements. Going down a main group, the effect of increasing nuclear charge is generally outweighed by the effect of additional electrons being further away from the nucleus. With some irregularities, atoms become larger, ionization energy falls, and metallic character increases. The combined effect of these competing horizontal and vertical trends is that the location of the metal-nonmetal transition zone shifts to the right in going down a group. A related effect can be seen in other diagonal similarities between some elements and their lower right neighbours, such as lithium-magnesium, beryllium-aluminium, carbon-phosphorus, and nitrogen-sulfur.

Number, composition and alternative treatments

How many and which elements are metalloids depends on the classification criteria being used. Emsley recognised four metalloids: germanium, arsenic, antimony and tellurium; James et al. listed twelve: boron, carbon, silicon, germanium, arsenic, selenium, antimony, tellurium, bismuth, polonium, ununpentium and livermorium. On average, seven elements are included in such lists. Although there is no standardized division of the elements into metals, metalloids and nonmetals, individual classification arrangements tend to share common ground, with most variations occurring around the indistinct margins.

Some authors do not classify elements bordering the metal-nonmetal dividing line as metalloids, noting that a binary classification can facilitate the establishment of rules for determining bond types between metals and nonmetals. Metalloids are grouped with metals, regarded as nonmetals or treated as a sub-category of nonmetals. Other authors have suggested that classifying some elements as metalloids 'emphasizes that properties change gradually rather than abruptly as one moves across or down the periodic table'. Some periodic tables distinguish elements that are metalloids in the absence of any formal dividing line between metals and nonmetals. Metalloids are shown as occurring in a diagonal band or diffuse region.

Properties of metalloids

Physical and chemical

Metalloids are usually characterised as metallic-looking brittle solids with intermediate to relatively good electrical conductivity values, and each having the electronic band structure of a semimetal or semiconductor. Chemically, they mostly behave as (weak) nonmetals, have intermediate ionization energies and electronegativity values, and have amphoteric or weakly acidic oxides. They can form alloys with metals. Most of the other physical and chemical properties of metalloids are intermediate in nature.

Distinctive

Brittleness, semiconductivity or both have been used as distinguishing indicators of metalloid status. Not all elements classified in the literature as metalloids display semiconductivity, although most do. Metallic lustre along with dualistic chemical behaviour—for example, amphoterism—has also been cited as a benchmark.

Metalloids are all solid, and have metallic lustre, but their other properties vary. Given that metallic character (for example) is a combination of several properties, it has been suggested that metalloid status be judged separately for each element. This could be done based on the extent to which an element exhibits properties relevant to such status.

Compared to metals and nonmetals

Main article: Metalloid (comparison of properties with those of metals and nonmetals)

Characteristic properties of metals, metalloids and nonmetals are summarized in the table. Physical properties are listed in order of ease of determination; chemical properties run from general to specific, and then to descriptive.

Properties of metals, metalloids and nonmetals

Physical property	Metals	Metalloids	Nonmetals
Form	solid; a few liquid at or near room temperature (Ga, Hg, Rb, Cs, Fr)	solid	mostly gases
Appearance	lustrous (at least when freshly fractured)	lustrous	several colourless; others coloured, or metallic grey to black
Elasticity	typically elastic, ductile, malleable (when solid)	brittle	brittle, if solid
Electrical conductivity	good to high	intermediate to good	poor to good
Band structure	metallic (Bi = semimetallic)	are semiconductors or, if not (As, Sb = semimetallic), exist in semiconducting forms	semiconductor or insulator
Chemical property	Metals	Metalloids	Nonmetals
General chemical behaviour	metallic	nonmetallic	nonmetallic
Ionization energy	relatively low	intermediate ionization energies, usually falling between those of metals and nonmetals	relatively high
Electronegativity	usually low	have electronegativity values close to 2 (revised Pauling scale) or within the range of 1.9–2.2 (Allen scale)	high
When mixed with metals	give alloys	can form alloys	ionic or interstitial compounds formed
Oxides	lower oxides basic; higher oxides increasingly acidic	amphoteric or weakly acidic	acidic

The metalloid properties for form, appearance, and behaviour when mixed with metals are more like metals. Elasticity and general chemical behaviour are more like nonmetals. Electrical conductivity, band structure, ionization energy, electronegativity, and oxides are intermediate between the two.

Typical or shared applications

Metalloids are too brittle to have any structural uses in their pure forms. They and their compounds are used as (or in) alloying components, biological agents (toxicological, nutritional and medicinal), flame retardants, glasses (oxide and metallic), optical storage media, semiconductors and electronics.

Alloys

Copper-germanium alloy pellets, likely ~84% Cu; 16% Ge. When combined with silver the result is a tarnish resistant sterling silver. Also present are two silver pellets.

Writing early in the history of intermetallic compounds, the British metallurgist Cecil Desch observed that 'certain non-metallic elements are capable of forming compounds of distinctly metallic character with metals, and these elements may therefore enter into the composition of alloys'. He associated silicon, arsenic and tellurium—in particular—with the alloy-forming elements. Compounds of silicon, germanium, arsenic and antimony with the poor metals, it has been suggested, 'are probably best classed as alloys.'

Alloys with transition metals are well-represented. Boron can form intermetallic compounds and alloys with such metals, of the composition M_nB, if n > 2. Ferroboron (15% boron) is used to introduce boron into steel; nickel-boron alloys are ingredients in welding alloys and case hardening compositions for the engineering industry. Alloys of silicon with iron, and with aluminium, are widely used by the steel and automotive industries, respectively. Germanium forms many alloys, most importantly with the coinage metals. Arsenic can form alloys with metals, including platinum and copper; it is also added to copper and its alloys to improve corrosion resistance and appears to confer the same benefit when added to magnesium. Antimony is well known as an alloy former, including with the coinage metals. Its alloys include pewter (a tin alloy with up to 20% antimony) and type metal (a lead alloy with up to 25% antimony). Tellurium readily alloys with iron, as ferrotellurium (50–58% tellurium), and with copper, in the form of copper tellurium (40–50% tellurium). Ferrotellurium is used as a stabilizer for carbon in steel casting. Of the non-metallic elements that are less often recognised as metalloids, selenium—in the form of ferroselenium (50–58% selenium)—is used to improve the workability of stainless steels.

Biological agents

Arsenic trioxide or white arsenic, one of the most toxic and prevalent forms of arsenic. The antileukaemic properties of white arsenic were first reported in 1878.

All six of the elements commonly recognised as metalloids have toxic, dietary or medicinal properties. Arsenic, and antimony compounds are especially toxic; boron, silicon, and possibly arsenic, are essential trace elements. Boron, silicon, arsenic and antimony have medical applications (with germanium and tellurium being thought to have potential).

Boron is used in insecticides and herbicides. It is an essential trace element. As boric acid, it has antiseptic, antifungal, and antiviral properties.

Silicon is present in silatrane, a highly toxic rodenticide. Long-term inhalation of silica dust causes silicosis, a fatal disease of the lungs. Silicon is an essential trace element. As a silicone gel it can be applied to badly burned patients to reduce scarring.

Salts of germanium are potentially harmful to humans and animals if ingested on a prolonged basis. Although there is interest in the pharmacological actions of germanium compounds, there is (as yet) no licensed medicine.

Arsenic is notoriously poisonous and may also be an essential element in ultratrace amounts. It has been used as a pharmaceutical agent since antiquity, including for the treatment of syphilis prior to the development of antibiotics. Arsenic is also a component of melarsoprol, a medicinal drug used in the treatment of human African trypanosomiasis or sleeping sickness. In 2003, arsenic trioxide (under the trade name Trisenox) was re-introduced for the treatment of acute promyelocytic leukaemia, a cancer of the blood and bone marrow.

Metallic antimony is relatively non-toxic but most antimony compounds are poisonous. Compounds of antimony are used as antiprotozoan drugs, and in some veterinary preparations.

Tellurium is not considered particularly toxic although as little as two grams of sodium tellurate, if administered, can be lethal. People exposed to small amounts of airborne tellurium exude a foul and persistent garlic-like odour. Tellurium dioxide has been used to treat seborrhoeic dermatitis; other tellurium compounds were used as antimicrobial agents before the development of antibiotics. In future, such compounds may need to be substituted for antibiotics that have become ineffective due to bacterial resistance.

Of the elements less often recognised as metalloids, beryllium and lead are noted for their toxicity, with lead arsenate having been extensively used as an insecticide. Sulfur is one of the oldest of the fungicides and pesticides. Phosphorus, sulfur, zinc and iodine are essential nutrients, as are possibly aluminium, tin and lead. Sulfur, gallium, iodine and bismuth have medicinal applications. Sulfur is a constituent of sulfonamide drugs, still widely used for conditions such as acne and urinary tract infections. Gallium nitrate is used to treat the side effects of cancer; gallium citrate, a radiopharmaceutical, facilitates imaging of inflamed body areas. Iodine is used as a disinfectant in various forms. Bismuth is an ingredient in some antibacterials.

Flame retardants

Compounds of boron, silicon, arsenic and antimony have been used as flame retardants. Boron, in the form of borax, has been used as a textile flame retardant since at least the 18th century. Silicon compounds such as silicones, silanes, silsesquioxane, silica and silicates, some of which were developed as alternatives to more toxic halogenated products, can considerably improve the flame retardancy of plastic materials. Arsenic compounds such as sodium arsenite or sodium arsenate are effective flame retardants for wood but were less frequently used due to their toxicity. Antimony trioxide is a flame retardant. Aluminium hydroxide has been used as a wood-fibre, rubber, plastic and textile flame retardant since the 1890s. Apart from aluminium hydroxide, use of phosphorus based flame-retardants in the form of, for example, organophosphates, now exceeds that of any of the other main retardant types, which employ boron, antimony or halogenated hydrocarbon compounds.

Glass formation

Optical fibres, usually made of pure silicon dioxide glass, with additives such as boron trioxide or germanium dioxide for increased sensitivity

The oxides B₂O₃, SiO₂, GeO₂, As₂O₃ and Sb₂O₃ readily form glasses. TeO₂ forms a glass but this requires a 'heroic quench rate' or the addition of an impurity, otherwise the crystalline form results. These compounds are used in chemical, domestic and industrial glassware and optics. Boron trioxide is used as a glass fibre additive; it is also a component of borosilicate glass, which is widely used for laboratory glassware and domestic ovenware. Most ordinary glassware is made from silicon dioxide. Germanium dioxide is used as a glass fibre additive, as well as in infrared optical systems. Arsenic trioxide is used in the glass industry as a decolourizing and fining agent, as is antimony trioxide. Tellurium dioxide finds application in laser and nonlinear optics.

Amorphous metallic glasses are generally most easily prepared if one of the components is a metalloid or 'near metalloid' such as boron, carbon, silicon, phosphorus or germanium. Aside from thin films deposited at very low temperatures, the first known metallic glass was an alloy of composition Au₇₅Si₂₅ reported in 1960. A metallic glass having a strength and toughness not previously seen, of composition Pd_82.5P₆Si_9.5Ge₂, was reported in 2011.

Phosphorus, selenium and lead, which are less often recognised as metalloids, are also used in glasses. Phosphate glass has a substrate of phosphorus pentoxide (P₂O₅), rather than the silica (SiO₂) of conventional silicate glasses and is used, for example, to make sodium lamps. Selenium compounds can be used both as decolourising agents and to add a red colour to glass. Decorative glassware made of traditional lead glass contains at least 30% lead(II) oxide (PbO); lead glass used for radiation shielding may have up to 65% PbO. Lead-based glasses have also been extensively used in electronics components; enamelling; sealing and glazing materials; and solar cells. Bismuth based oxide glasses have emerged as a less toxic replacement for lead in many of these applications.

Optical storage

Varying compositions of GeSbTe ("GST alloys") and Ag- and In- doped Sb₂Te ("AIST alloys"), being examples of phase-change materials, are widely used in rewritable optical discs and phase-change memory devices. By applying heat, they can be switched between amorphous (glassy) and crystalline states. The change in optical and electrical properties can be used for information storage purposes.

Semiconductors and electronics

Semiconductor-based electronic components. From left to right: a transistor, an integrated circuit and an LED. The elements commonly recognised as metalloids find widespread use in such devices, as elemental or compound semiconductor constituents (Si, Ge or GaAs, for example) or as doping agents (B, Sb, Te, for example).

All the elements commonly recognised as metalloids (or their compounds) have been used in the semiconductor or solid-state electronic industries. Some properties of boron have limited its use as a semiconductor. It has a high melting point, single crystals are relatively hard to obtain, and introducing and retaining controlled impurities is difficult. Silicon is the leading commercial semiconductor; it forms the basis of modern electronics (including standard solar cells) and information and communication technologies. This was despite the study of semiconductors, early in the 20th century, having been regarded as the 'physics of dirt' and not deserving of close attention. Silicon has largely replaced germanium in semiconducting devices, being cheaper, more resilient at higher operating temperatures, and easier to work during the microelectronic fabrication process. Germanium is however a constituent of semiconducting silicon-germanium 'alloys' and these have been growing in use, particularly for wireless communication devices; such alloys exploit the higher carrier mobility of germanium. The synthesis of gram-scale quantities of semiconducting germanane was reported in 2013. This comprises one-atom thick sheets of hydrogen-terminated germanium atoms, analogous to graphane. It conducts electrons more than ten times faster than silicon and five times faster than germanium, and is thought to have potential for optoelectronic and sensing applications.

Although arsenic and antimony are not semiconductors in their standard states, both form type III-V semiconductors (such as GaAs, AlSb or GaInAsSb) in which the average number of valence electrons per atom is the same as that of Group 14 elements. These compounds are preferred for some special applications. Tellurium, which is a semiconductor in its standard state, is used mainly as a component in type II/VI semiconducting-chalcogenides; these have applications in electro-optics and electronics. Cadmium telluride (CdTe) is used in solar modules for its high conversion efficiency, low manufacturing costs, and large band gap of 1.44 eV, letting it absorb a wide range of wavelengths. Bismuth telluride (Bi₂Te₃), alloyed with selenium and antimony, is a component of thermoelectric devices, used for refrigeration or portable power generation. Five metalloids—boron, silicon, germanium, arsenic and antimony—can be found in cell phones (along with at least 39 other metals and nonmetals). Tellurium is expected to find such use. Of the less often recognised metalloids, phosphorus, gallium (in particular) and selenium have semiconductor applications. Phosphorus is used in trace amounts as a dopant for n-type semiconductors. The commercial use of gallium compounds is dominated by semiconductor applications—in integrated circuits; cell phones; laser diodes; light emitting diodes; photodetectors; and solar cells. Selenium is used in the production of solar cells and in high-energy surge protectors.

Nomenclature and history

Derivation and other names

The word metalloid comes from the Latin metallum ("metal") and the Greek oeides ("resembling in form or appearance"). The terms amphoteric element, boundary element, half-metal, half-way element, near metal, meta-metal, semiconductor, semimetal and submetal are sometimes used synonymously although some of these have other meanings that may not be interchangeable. 'Amphoteric element' is sometimes used more broadly to include transition metals capable of forming oxyanions, such as chromium and manganese. 'Half-metal' is used in physics to refer to a compound (such as chromium dioxide) or alloy that can act as a conductor and an insulator. 'Meta-metal' is sometimes used instead to refer to certain metals (Be, Zn, Cd, Hg, In, Tl, β-Sn, Pb) located just to the left of the metalloids on standard periodic tables. These metals are mostly diamagnetic and tend to have distorted crystalline structures, electrical conductivity values at the lower end of those of metals, and amphoteric (weakly basic) oxides. 'Semimetal' sometimes refers, loosely or explicitly, to metals with incomplete metallic character in crystalline structure, electrical conductivity or electronic structure. Examples include gallium, ytterbium, bismuth and neptunium. The terms amphoteric element and semiconductor are problematic as some elements referred to as metalloids do not show marked amphoteric behaviour or semiconductivity in their most stable forms.

Origin and usage

Main article: Metalloid (nomenclature origin and usage)

The origin and usage of the term 'metalloid' is convoluted. Its origin lies in attempts, dating from antiquity, to describe metals and to distinguish between typical and less typical forms. It was first applied in the early 19th century to metals that floated on water (sodium and potassium), and then more popularly to nonmetals. Earlier usage in mineralogy, to describe a mineral having a metallic appearance, can be sourced to as early as 1800. Since the mid-20th century it has been used to refer to intermediate or borderline chemical elements. The International Union of Pure and Applied Chemistry (IUPAC) previously recommended abandoning the term metalloid, and suggested using the term 'semimetal' instead. Use of this latter term has more recently been discouraged as it has a different meaning in physics—one that more specifically refers to the electronic band structure of a substance rather than the overall classification of an element. The most recent IUPAC publications on nomenclature and terminology do not include any recommendations on the usage of the terms 'metalloid' or 'semimetal'.

Elements commonly recognised as metalloids

Properties noted in this section refer to the elements in their most thermodynamically stable forms under ambient conditions.

Boron

Main article: Boron

Boron, shown here in the form of its β-rhombohedral phase (its most thermodynamically stable allotrope)

Pure boron is a shiny, silver-grey crystalline solid. It is less dense than aluminium (2.34 v 2.70 g/cm³), and is hard and brittle. It is barely reactive under normal conditions, except for attack by fluorine, and has a melting point of 2076 °C (cf. steel ~1370 °C). Boron is a semiconductor, with a room temperature electrical conductivity of 1.5 × 10⁻⁶ S•cm⁻¹ (about 200 times less than that of tap water) and a band gap of about 1.56 eV.

The chemistry of boron is dominated by its small atomic size, relatively high ionization energy, and having fewer valence electrons (three) than atomic orbitals (four) available for bonding. With only three valence electrons, simple covalent bonding is electron deficient with respect to the octet rule. Elements in this situation usually adopt metallic bonding, but the small size and high ionization energies of boron tends to instead result in delocalized covalent bonding, in which three atoms share two electrons. The associated structural component that pervades the various allotropes of boron is the icosahedral B₁₂ unit. This also occurs, as do deltahedral variants or fragments, in several metal borides, certain hydrides, and some halides. The bonding in boron has been described as being characteristic of behaviour intermediate between metals and nonmetallic covalent network solids (such as diamond). The energy required to transform B, C, N, Si and P from nonmetallic to metallic states has been estimated as 30, 100, 240, 33 and 50 kJ/mol, respectively. This indicates how close boron is to the metal-nonmetal borderline.

Most of the chemistry of boron is nonmetallic in nature. The small size of the boron atom enables the preparation of many interstitial alloy-type borides. Analogies between boron and transition metals have been noted in the formation of complexes, and adducts (for example, BH₃ + CO →BH₃CO and, similarly, Fe(CO)₄ + CO →Fe(CO)₅), as well as in the geometric and electronic structures of cluster species such as [B₆H₆]^2– and [Ru₆(CO)₁₈]^2–. The aqueous chemistry of boron is characterised by the formation of many different polyborate anions. Given its high charge-to-size ratio, nearly all compounds of boron are covalent, with a few complexed anionic and cationic species. Boron has a strong affinity for oxygen and a duly extensive borate chemistry. The oxide B₂O₃ is polymeric in structure, weakly acidic, and a glass former. Organometallic compounds of boron have been known since the 19th century (see organoboron chemistry).

Silicon

Main article: Silicon

Silicon has a shiny blue-grey metallic lustre.

Silicon is a shiny crystalline solid, with a blue-grey metallic lustre. Like boron, it is less dense than aluminium (2.33 v 2.70 g/cm³), and is hard and brittle. It is a relatively unreactive element, the massive, crystalline form (especially if pure) being 'remarkably inert to all acids, including hydrofluoric'. Less pure silicon, and the powdered form, are variously susceptible to attack by strong or heated acids, as well as by steam and fluorine. Silicon dissolves in hot aqueous alkalis with the evolution of hydrogen, as do metals such as beryllium, aluminium, zinc, gallium or indium. It melts at 1414 °C. Silicon is a semiconductor with an electrical conductivity of 10⁻⁴ S•cm⁻¹ and a band gap of about 1.11 eV. When it melts, silicon becomes a reasonable metal with an electrical conductivity of 1.0–1.3 × 10⁴ S•cm⁻¹, similar to that of liquid mercury.

The chemistry of silicon is generally nonmetallic (covalent) in nature. It can form alloys with metals such as iron and copper. Silicon shows fewer tendencies to anionic behaviour than ordinary nonmetals. Its solution chemistry is characterised by the formation of oxyanions. The high strength of the silicon-oxygen bond dominates the chemical behaviour of silicon. Polymeric silicates, built up by tetrahedral SiO₄ units sharing their oxygen atoms, are the most abundant and important compounds of silicon. The polymeric borates, comprising linked trigonal and tetrahedral BO₃ or BO₄ units, are built on similar structural principles. The oxide SiO₂ is polymeric in structure, weakly acidic, and a glass former. Traditional organometallic chemistry includes the carbon compounds of silicon (see organosilicon).

Germanium

Main article: Germanium

Germanium is sometimes described as a metal.

Germanium is a shiny grey-white solid. It has a density of 5.323 g/cm³ and is hard and brittle. It is mostly unreactive at room temperature but is slowly attacked by hot concentrated sulfuric or nitric acid. Germanium also reacts with molten caustic soda to yield sodium germanate Na₂GeO₃, together with the evolution of hydrogen. It melts at 938 °C. Germanium is a semiconductor with an electrical conductivity of around 2 × 10⁻² S•cm⁻¹ and a band gap of 0.67 eV. Liquid germanium is a metallic conductor, with an electrical conductivity on par with that of liquid mercury.

Most of the chemistry of germanium is characteristic of a nonmetal. It can form alloys with metals such as aluminium and gold. Germanium shows fewer tendencies to anionic behaviour than ordinary nonmetals. Its solution chemistry is characterised by the formation of oxyanions. Germanium generally forms tetravalent (IV) compounds, and it can also form less stable divalent (II) compounds, in which it behaves more like a metal. Germanium analogues of all of the major types of silicates have been prepared. The metallic character of germanium is also suggested by the formation of various oxoacid salts. A phosphate [(HPO₄)₂Ge·H₂O] and highly stable trifluoroacetate Ge(OCOCF₃)₄ have been described, as have Ge₂(SO₄)₂, Ge(ClO₄)₄ and GeH₂(C₂O₄)₃. The oxide GeO₂ is polymeric, amphoteric, and a glass former. The dioxide is soluble in acidic solutions (the monoxide GeO, is even more so), and this is sometimes used as a basis to classify germanium as a metal. Up to the 1930s germanium was in fact considered to be a poorly conducting metal rather than a nonmetal. As is the case with all the elements commonly recognised as metalloids, germanium has an established organometallic chemistry (see organogermanium chemistry).

Arsenic

Main article: Arsenic

Arsenic, sealed in a container to prevent tarnishing

Arsenic is a grey, metallic looking solid. It has a density of 5.727 g/cm³ and is brittle, and moderately hard (more than aluminium; less than iron). It is stable in dry air but develops a golden bronze patina in moist air, which blackens on further exposure. Arsenic is attacked by nitric acid and concentrated sulfuric acid. It reacts with fused caustic soda to give the arsenate Na₃AsO₃, together with the evolution of hydrogen. Arsenic sublimes at 615 °C. The vapour is lemon-yellow and smells like garlic. Arsenic only melts under a pressure of 38.6 atm, at 817 °C. It is a semimetal with an electrical conductivity of around 3.9 × 10⁴ S•cm⁻¹ and a band overlap of 0.5 eV. Liquid arsenic is a semiconductor with a band gap of 0.15 eV.

The chemistry of arsenic is predominately nonmetallic. It can form alloys with many metals; most of these are brittle. Arsenic shows fewer tendencies to anionic behaviour than ordinary nonmetals. Its solution chemistry is characterised by the formation of oxyanions. Arsenic generally forms compounds in which it has an oxidation state of +3 or +5. The halides, and the oxides and their derivatives are illustrative examples. In the trivalent state, arsenic shows some incipient metallic properties. The halides are hydrolysed by water but these reactions, particularly those of the chloride, are reversible with the addition of a hydrohalic acid. The oxide is acidic but, as noted below, (weakly) amphoteric. The higher, less stable, pentavalent state has strongly acidic (nonmetallic) properties. Compared to phosphorus, the stronger metallic character of arsenic is indicated by the formation of oxoacid salts such as AsPO₄, As₂(SO₄)₃ and arsenic acetate As(CH₃COO)₃. The oxide As₂O₃ is polymeric, amphoteric, and a glass former. Arsenic has an extensive organometallic chemistry (see organoarsenic chemistry).

Antimony

Main article: Antimony

Antimony, showing its brilliant lustre

Antimony is a silver-white solid with a blue tint and a brilliant lustre. It has a density of 6.697 g/cm³ and is brittle, and moderately hard (more so than arsenic; less so than iron; about the same as copper). It is stable in air and moisture at room temperature. It is attacked by concentrated nitric acid, yielding the hydrated pentoxide Sb₂O₅. Aqua regia gives the pentachloride SbCl₅ and hot concentrated sulfuric acid results in the sulfate Sb₂(SO₄)₃. It is not affected by molten alkali. Antimony is capable of displacing hydrogen from water, when heated: 2 Sb + 3 H₂O → Sb₂O₃ + 3 H₂. It melts at 631 °C. Antimony is a semimetal with an electrical conductivity of around 3.1 × 10⁴ S•cm⁻¹ and a band overlap of 0.16 eV. Liquid antimony is a metallic conductor with an electrical conductivity of around 5.3 × 10⁴ S•cm⁻¹.

Most of the chemistry of antimony is characteristic of a nonmetal. It can form alloys with one or more metals such as aluminium, iron, nickel, copper, zinc, tin, lead and bismuth. Antimony has fewer tendencies to anionic behaviour than ordinary nonmetals. Its solution chemistry is characterised by the formation of oxyanions. Like arsenic, antimony generally forms compounds in which it has an oxidation state of +3 or +5. The halides, and the oxides and their derivatives are illustrative examples. The +5 state is less stable than the +3, but relatively easier to attain than with arsenic. This is explained by the poor shielding afforded the arsenic nucleus by its 3d¹⁰ electrons. In comparison, the tendency of antimony to oxidize more easily partially offsets the effect of its 4d¹⁰ shell. Tripositive antimony is amphoteric; pentapositive antimony is (predominately) acidic. Consistent with an increase in metallic character down group 15, antimony forms salts or salt-like compounds including a nitrate Sb(NO₃)₃, phosphate SbPO₄, sulfate Sb₂(SO₄)₃ and perchlorate Sb(ClO₄)₃. The otherwise acidic pentoxide Sb₂O₅ shows some basic (metallic) behaviour in that it can be dissolved in very acidic solutions, with the formation of the oxycation SbO⁺
₂. The oxide Sb₂O₃ is a polymeric, amphoteric, and a glass former. Antimony has an extensive organometallic chemistry (see organoantimony chemistry).

Tellurium

Main article: Tellurium

Tellurium, described by Dmitri Mendeleev as forming a transition between metals and nonmetals

Tellurium is a silvery-white shiny solid. It has a density of 6.24 g/cm³, is brittle, and is the softest of the commonly recognised metalloids, being marginally harder than sulfur. Large pieces of tellurium are stable in air. The finely powdered form is oxidized by air in the presence of moisture. Tellurium reacts with boiling water, or when freshly precipitated even at 50 °C, to give the dioxide and hydrogen: Te + 2 H₂O → TeO₂ + 2 H₂. It reacts (to varying degrees) with nitric, sulfuric and hydrochloric acids to give compounds such as the sulfoxide TeSO₃ or tellurous acid H₂TeO₃, the basic nitrate (Te₂O₄H)⁺(NO₃)^–, or the oxide sulfate Te₂O₃(SO₄). It dissolves in boiling alkalis, with the formation of the tellurite and telluride: 3 Te + 6 KOH = K₂TeO₃ + 2 K₂Te + 3 H₂O, a reaction that proceeds or is reversible with increasing or decreasing temperature. At higher temperatures tellurium is sufficiently plastic to extrude. It melts at 449.51 °C. Crystalline tellurium has a structure consisting of parallel infinite spiral chains. Whereas the bonding between adjacent atoms in a chain is covalent, there is evidence of a weak metallic interaction between the neighbouring atoms of different chains. Tellurium is a semiconductor with an (intrinsic) electrical conductivity of around 1.0 S•cm⁻¹ and a band gap of 0.32 to 0.38 eV. Liquid tellurium is a semiconductor, with an electrical conductivity, on melting, of around 1.9 × 10³ S•cm⁻¹ Superheated liquid tellurium is a metallic conductor.

Most of the chemistry of tellurium is characteristic of a nonmetal. It can form alloys with aluminium, silver and tin. Tellurium shows fewer tendencies to anionic behaviour than ordinary nonmetals. Its solution chemistry is characterised by the formation of oxyanions. Tellurium generally forms compounds in which it has an oxidation state of −2, +4 or +6, with the tetrapositive state being the most stable. It combines easily with most other elements to form binary tellurides X_xTe_y these representing the most common mineral form. Non-stoichiometry is frequently encountered. This is particularly so with the transition metals, where electronegativity differences are small and irregular valence is favoured. Many of the associated tellurides can be treated as metallic alloys. The increase in metallic character evident in tellurium, as compared to the lighter chalcogens, is further reflected in the reported formation of various other oxyacid salts, such as a basic selenate 2TeO₂·SeO₃ and an analogous perchlorate and periodate 2TeO₂·HXO₄. Tellurium forms a polymeric, amphoteric, glass-forming oxide TeO₂. The latter is a 'conditional' glass-forming oxide—it forms a glass with a very small amount of additive. Tellurium has an extensive organometallic chemistry (see organotellurium chemistry).

Elements less commonly recognised as metalloids

Carbon

Main article: Carbon

Carbon (as graphite). Delocalized valence electrons within the layers of graphite give it a metallic appearance.

Carbon is ordinarily classified as a nonmetal but has some metallic properties and is occasionally classified as a metalloid. Hexagonal graphitic carbon is the most thermodynamically stable allotrope of carbon under ambient conditions. It has a lustrous appearance and is a fairly good electrical conductor. Graphite has a layered structure. Each layer comprises carbon atoms bonded to three other carbon atoms in a honeycomb lattice arrangement. The layers are stacked together and held loosely by van der Waals forces and delocalized valence electrons. Like a metal, the conductivity of graphite in the direction of its planes decreases as the temperature is raised; it has the electronic band structure of a semimetal. The allotropes of carbon, including graphite, can accept foreign atoms or compounds into their structures via substitution, intercalation or doping (interstitial or intrastitial) with the resulting materials being referred to as 'carbon alloys'. Carbon can form ionic salts, including a sulfate, perchlorate, nitrate, hydrogen selenate, and hydrogen phosphate. In organic chemistry, carbon can form complex cations—termed carbocations—in which the positive charge is on the carbon atom; examples are CH⁺
₃ and CH⁺
₅, and their derivatives.

Carbon is brittle, and behaves as a semiconductor in a direction perpendicular to its planes. Most of its chemistry is nonmetallic; it has a relatively high ionization energy and, compared to most metals, a relatively high electronegativity. Carbon can form anions such as C^4– (methanide), C^2–
₂ (acetylide) and C^3–
₄ (sesquicarbide or allylenide), in compounds with metals of main groups 1–3, and with the lanthanides and actinides. Its oxide CO₂ forms a medium-strength carbonic acid H₂CO₃.

Aluminium

Main article: Aluminium

People handling high purity aluminium for the first time often question if it really is aluminium since it is very much softer than its familiar alloys.

Aluminium is classified as a metal. It is lustrous, malleable and ductile, has high electrical and thermal conductivity and a close-packed crystalline structure.

It has some properties that are unusual for a metal; taken together, these properties are sometimes used as a basis to classify aluminium as a metalloid. Its crystalline structure shows some evidence of directional bonding. Although it forms an Al³⁺ cation in some compounds, aluminium bonds covalently in most others. Its oxide is amphoteric, and a conditional glass-former. Aluminium can form anionic aluminates, such behaviour being considered nonmetallic in character.

Stott labels aluminium as a weak metal. It has the physical properties of a metal but some of the chemical properties of a nonmetal. Steele notes the paradoxical chemical behaviour of aluminium. It resembles a weak metal with its amphoteric oxide and the covalent character of many of its compounds. Yet it is also a strongly electropositive metal, with a high negative electrode potential.

Classifying aluminium as a metalloid is disputed as it has many metallic properties. It is therefore, arguably, an exception to the mnemonic that elements adjacent to the metal-nonmetal dividing line are metalloids.

Selenium

Main article: Selenium

Selenium. Being a photoconductor, grey selenium conducts electricity around 1,000 times better when light falls on it, a property used since the mid-1870s in various light-sensing applications.

Selenium shows borderline metalloid or nonmetal behaviour.

Its most stable form, the grey trigonal allotrope, is sometimes called 'metallic' selenium. This is because its electrical conductivity is several orders of magnitude greater than that of the red monoclinic form. The metallic character of selenium is further shown by its lustre and its crystalline structure, the latter of which is thought to include weakly 'metallic' interchain bonding. Selenium can be drawn into thin threads when molten. It shows reluctance to acquire 'the high positive oxidation numbers characteristic of nonmetals'. It can form cyclic polycations (such as Se²⁺
₈) when dissolved in oleums (an attribute it shares with sulfur and tellurium), and a hydrolysed cationic salt in the form of trihydroxoselenium (IV) perchlorate [Se(OH)₃]⁺·ClO^–
₄.

The nonmetallic character of selenium is shown by its brittleness and the low electrical conductivity (~10⁻⁹ to 10⁻¹² S•cm⁻¹) of its highly purified form. This is comparable to or less than that of bromine (7.95×10^–12 S•cm⁻¹), a nonmetal. Selenium has the electronic band structure of a semiconductor and retains its semiconducting properties in liquid form. It has a relatively high electronegativity (2.55 revised Pauling scale). Its reaction chemistry is mainly that of its nonmetallic anionic forms Se^2–, SeO²⁻
₃ and SeO²⁻
₄.

Selenium is commonly described as a metalloid in the environmental chemistry literature. It moves through the aquatic environment like arsenic and antimony do. Its water-soluble salts, in higher concentrations, have a toxicological profile similar to that of arsenic.

Polonium

Main article: Polonium

Polonium, in the form of a thin film on a stainless-steel disc

Polonium is 'distinctly metallic' in some ways. Both of its allotropic forms are metallic conductors. It is soluble in acids, forming the rose-coloured Po²⁺ cation and displacing hydrogen: Po + 2 H⁺ → Po²⁺ + H₂. Many polonium salts are known. The oxide PoO₂ is predominantly basic in nature. Polonium is a reluctant oxidizing agent, unlike its lighter congener oxygen: highly reducing conditions are required for the formation of the Po^2– anion in aqueous solution.

Polonium also shows nonmetallic character in its halides, and by way of the existence of polonides. The halides have properties generally characteristic of nonmetal halides (being volatile, easily hydrolyzed, and soluble in organic solvents). Many metal polonides, obtained by heating the elements together at 500–1,000 °C, and containing the Po^2– anion, are also known.

Astatine

Main article: Astatine

Astatine, which is ordinarily classified as a nonmetal has some marked metallic properties and may be more appropriately classified as either a metalloid or a metal. Immediately following its production in 1940, early investigators considered it a metal. In 1949 it was called the most noble (difficult to reduce) nonmetal as well as being a relatively noble (difficult to oxidize) metal. In 1950 astatine was described as a halogen and (therefore) a reactive nonmetal. In 2013, on the basis of relativistic modelling, astatine was predicted to be a monatomic metal, with a face-centred cubic crystalline structure.

Several authors have commented on the metallic nature of some of the properties of astatine. Since iodine is a semiconductor in the direction of its planes, and since the halogens become more metallic with increasing atomic number, it has been presumed that astatine would be a metal if it could form a condensed phase. Astatine may be metallic in the liquid state on the basis that elements with an enthalpy of vaporization (EoV) greater than ~42 kJ/mol are metallic when liquid. Such elements include boron, silicon, germanium, antimony, selenium and tellurium. Estimated values for the EoV of diatomic astatine are 50 kJ/mol or higher; diatomic iodine, with an EoV of 41.71, falls just short of the threshold figure. '[L]ike typical metals, it [astatine] is precipitated by hydrogen sulfide even from strongly acid solutions and is displaced in a free form from sulfate solutions; it is deposited on the cathode on electrolysis'. Further indications of a tendency for astatine to behave like a (heavy) metal are: '...the formation of pseudohalide compounds...complexes of astatine cations...complex anions of trivalent astatine...as well as complexes with a variety of organic solvents'. It has also been argued that astatine demonstrates cationic behaviour, by way of stable At⁺ and AtO⁺ forms, in strongly acidic aqueous solutions.

Some of astatine's reported properties are nonmetallic. It has the narrow liquid range ordinarily associated with nonmetals (mp 302 °C; bp 337 °C). Batsanov gives a calculated band gap energy for astatine of 0.7 eV; this is consistent with nonmetals (in physics) having separated valence and conduction bands and thereby being either semiconductors or insulators. The chemistry of astatine in aqueous solution is mainly characterised by the formation of various anionic species. Most of its known compounds resemble those of iodine, which is a halogen and a nonmetal. Such compounds include astatides (XAt), astatates (XAtO₃), and monovalent interhalogen compounds.

Restrepo et al. reported that astatine appeared to be more polonium-like than halogen-like. They did so on the basis of detailed comparative studies of the known and interpolated properties of 72 elements.

Honourable mentions

Elements near the metalloids

Iodine crystals, showing a metallic lustre. Iodine is a semiconductor in the direction of its planes, with a band gap of ~1.3 eV. It has an electrical conductivity of 1.7 × 10⁻⁸ S•cm⁻¹ at room temperature. This is higher than selenium but lower than boron, the least electrically conducting of the recognised metalloids.

In the periodic table, some of the elements adjacent to the commonly recognised metalloids, although usually classified as either metals or nonmetals, are occasionally referred to as near-metalloids or noted for their metalloidal character. To the left of the metal-nonmetal dividing line, such elements include gallium, tin and bismuth. They show unusual packing structures, marked covalent chemistry (molecular or polymeric), and amphoterism. To the right of the dividing line are carbon, phosphorus, selenium and iodine. They exhibit metallic lustre, semiconducting properties and bonding or valence bands with delocalized character. This applies to their most thermodynamically stable forms under ambient conditions: carbon as graphite; phosphorus as black phosphorus; and selenium as grey selenium.

Allotropes

White tin (left) and grey tin (right). Both forms have a metallic appearance.

Different crystalline forms of an element are called allotropes. Some allotropes, particularly those of elements located (in periodic table terms) alongside or near the notional dividing line between metals and nonmetals, exhibit more pronounced metallic, metalloidal or nonmetallic behaviour than others. The existence of such allotropes can complicate the classification of the elements involved.

Tin, for example, has two allotropes: tetragonal 'white' β-tin and cubic 'grey' α-tin. White tin is a very shiny, ductile and malleable metal. It is the stable form at or above room temperature and has an electrical conductivity of 9.17×10⁴ S·cm⁻¹ (~1/6th that of copper). Grey tin usually has the appearance of a grey micro-crystalline powder, and can also be prepared in brittle semi-lustrous crystalline or polycrystalline forms. It is the stable form below 13.2 °C and has an electrical conductivity of between (2–5)×10² S·cm⁻¹ (~1/250th that of white tin). Grey tin has the same crystalline structure as that of diamond. It behaves as a semiconductor (with a band gap of 0.08 eV), but has the electronic band structure of a semimetal. It has been referred to as either a very poor metal, a metalloid, a nonmetal or a near metalloid.

The diamond allotrope of carbon is clearly nonmetallic, being translucent and having a low electrical conductivity of 10⁻¹⁴ to 10⁻¹⁶ S·cm⁻¹. Graphite has an electrical conductivity of 3×10⁴ S·cm⁻¹, a figure more characteristic of a metal. Phosphorus, sulfur, arsenic, selenium, antimony and bismuth also have less stable allotropes that display different behaviours.

References

• Addison WE 1964, The Allotropy of the Elements, Oldbourne Press, London
• Addison CC & Sowerby DB 1972, Main Group Elements: Groups V and VI, Butterworths, London, ISBN 0839110057
• Adler D 1969, 'Half-way Elements: The Technology of Metalloids', book review, Technology Review, vol. 72, no. 1, Oct/Nov, pp. 18–19, ISSN 00401692
• Ahmed MAK, Fjellvåg H & Kjekshus A 2000, 'Synthesis, Structure and Thermal Stability of Tellurium Oxides and Oxide Sulfate Formed from Reactions in Refluxing Sulfuric Acid', Journal of the Chemical Society, Dalton Transactions, no. 24, pp. 4542–9, doi:10.1039/B005688J
• Aldridge BG 1998, Science Interactions: Course 2, 3rd ed., Glencoe/McGraw-Hill, Westerville, Ohio, ISBN 9780028281575
• Allen DS & Ordway RJ 1968, Physical Science, 2nd ed., Van Nostrand, Princeton, New Jersey, ISBN 9780442002909
• Allen PB & Broughton JQ 1987, 'Electrical Conductivity and Electronic Properties of Liquid Silicon', Journal of Physical Chemistry, vol. 91, no. 19, pp. 4964–70, doi:10.1021/j100303a015
• Alloul H 2010, Introduction to the Physics of Electrons in Solids, Springer-Verlag, Berlin, ISBN 3642135641
• Anderson JB, Rapposch MH, Anderson CP & Kostiner E 1980, 'Crystal Structure Refinement of Basic Tellurium Nitrate: A Reformulation as (Te₂O₄H)⁺(NO₃)⁻', Monatshefte für Chemie/ Chemical Monthly, vol. 111, no. 4, pp. 789–96, doi:10.1007/BF00899243
• Antman KH 2001, 'Introduction: The History of Arsenic Trioxide in Cancer Therapy', The Oncologist, vol. 6, suppl. 2, pp. 1–2, doi:10.1634/theoncologist.6-suppl_2-1
• Apseloff G 1999, 'Therapeutic Uses of Gallium Nitrate: Past, Present, and Future', American Journal of Therapeutics, vol. 6, no. 6, pp. 327–39, ISSN 15363686
• Arlman EJ 1939, 'The Complex Compounds P(OH)₄.ClO₄ and Se(OH)₃.ClO₄', Recueil des Travaux Chimiques des Pays-Bas, vol. 58, no. 10, pp. 871–4, ISSN 01650513
• Askeland DR, Fulay PP & Wright JW 2011, The Science and Engineering of Materials, 6th ed., Cengage Learning, Stamford, CT, ISBN 0495668022
• Asmussen J & Reinhard DK 2002, Diamond Films Handbook, Marcel Dekker, New York, ISBN 0824795776
• Atkins P, Overton T, Rourke J, Weller M & Armstrong F 2006, Shriver & Atkins' Inorganic Chemistry, 4th ed., Oxford University Press, Oxford, ISBN 0716748789
• Atkins P, Overton T, Rourke J, Weller M & Armstrong F 2010, Shriver & Atkins' Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, ISBN 1429218207
• Austen K 2012, 'A Factory for Elements that Barely Exist', New Scientist, 21 Apr, p. 12
• Ba LA, Döring M, Jamier V & Jacob C 2010, 'Tellurium: an Element with Great Biological Potency and Potential', Organic & Biomolecular Chemistry, vol. 8, pp. 4203–16, doi:10.1039/C0OB00086H
• Bagnall KW 1957, Chemistry of the Rare Radioelements: Polonium-actinium, Butterworths Scientific Publications, London
• Bagnall KW 1966, The Chemistry of Selenium, Tellurium and Polonium, Elsevier, Amsterdam
• Bagnall KC 1990, 'Compounds of Polonium', in KC Buschbeck & C Keller (eds), Gmelin Handbook of Inorganic and Organometallic Chemistry, 8th ed., Po Polonium, Supplement vol. 1, Springer-Verlag, Berlin, pp. 285–340, ISBN 3540936165
• Bailar JC, Moeller T & Kleinberg J 1965, University Chemistry, DC Heath, Boston
• Bailar JC & Trotman-Dickenson AF 1973, Comprehensive Inorganic Chemistry, vol. 4, Pergamon, Oxford
• Bailar JC, Moeller T, Kleinberg J, Guss CO, Castellion ME & Metz C 1989, Chemistry, 3rd ed., Harcourt Brace Jovanovich, San Diego, ISBN 0155064568
• Barfuß H, Böhnlein G, Freunek P, Hofmann R, Hohenstein H, Kreische W, Niedrig H and Reimer A 1981, 'The Electric Quadrupole Interaction of ¹¹¹Cd in Arsenic Metal and in the System Sb_1–xIn_x and Sb_1–xCd_x', Hyperfine Interactions, vol. 10, nos 1–4, pp. 967–72, doi:10.1007/BF01022038
• Barrett J 2003, Inorganic Chemistry in Aqueous Solution, The Royal Society of Chemistry, Cambridge, ISBN 085404471X
• Barsanov GP & Ginzburg AI 1974, 'Mineral', in AM Prokhorov (ed.), Great Soviet Encyclopedia, 3rd ed., vol. 16, Macmillan, New York, pp. 329–32
• Bassett LG, Bunce SC, Carter AE, Clark HM & Hollinger HB 1966, Principles of Chemistry, Prentice-Hall, Englewood Cliffs, New Jersey
• Batsanov SS 1971, 'Quantitative Characteristics of Bond Metallicity in Crystals', Journal of Structural Chemistry, vol. 12, no. 5, pp. 809–13, doi:10.1007/BF00743349
• Becker WM, Johnson VA & Nussbaum 1971, 'The Physical Properties of Tellurium', in WC Cooper (ed.), Tellurium, Van Nostrand Reinhold, New York
• Belpassi L, Tarantelli F, Sgamellotti A & Quiney HM 2006, 'The Electronic Structure of Alkali Aurides. A Four-Component Dirac−Kohn−Sham study', The Journal of Physical Chemistry A, vol. 110, no. 13, April 6, pp. 4543–54, doi:10.1021/jp054938w
• Berger LI 1997, Semiconductor Materials, CRC Press, Boca Raton, Florida, ISBN 0849389127
• Bianco E, Butler S, Jiang S, Restrepo OD, Windl W & Goldberger JE 2013, 'Stability and Exfoliation of Germanane: A Germanium Graphane Analogue,' ACS Nano, March 19 (web), doi:10.1021/nn4009406
• Bodner GM & Pardue HL 1993, Chemistry, An Experimental Science, John Wiley & Sons, New York, ISBN 0471593869
• Bogoroditskii NP & Pasynkov VV 1967, Radio and Electronic Materials, Iliffe Books, London
• Boikess RS & Edelson E 1985, Chemical Principles, 3rd ed., Harper & Row, New York, ISBN 0060408057
• Bomgardner MM 2013, 'Thin-Film Solar Firms Revamp To Stay In The Game', Chemical & Engineering News, vol. 91, no. 20, pp. 20–1, ISSN 00092347
• Bond GC 2005, Metal-Catalysed Reactions of Hydrocarbons, Springer, New York, ISBN 0387241418
• Booth VH & Bloom ML 1972, Physical Science: A Study of Matter and Energy, Macmillan, New York
• Born M & Wolf E 1999, Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light, 7th ed., Cambridge University Press, Cambridge, ISBN 0521642221
• Borst KE 1982, 'Characteristic Properties of Metallic Crystals', Journal of Educational Modules for Materials Science and Engineering, vol. 4, no. 3, pp. 457–92, ISSN 01973940
• Bowser JR 1993, Inorganic Chemistry, Brooks/Cole, Pacific Grove, California, ISBN 0534175325
• Boyer RD, Li J, Ogata S & Yip S 2004, 'Analysis of Shear Deformations in Al and Cu: Empirical Potentials Versus Density Functional Theory', Modelling and Simulation in Materials Science and Engineering, vol. 12, no. 5, pp. 1017–29, doi:10.1088/0965-0393/12/5/017
• Boylan PJ 1962, Elements of Chemistry, Allyn & Bacon, Boston
• Bradbury GM, McGill MV, Smith HR & Baker PS 1957, Chemistry and You, Lyons and Carnahan, Chicago
• Brady JE, Senese F & Jespersen ND 2009, Chemistry: Matter and its Changes, John Wiley & Sons, Hoboken, New Jersey, ISBN 9780470120941
• Bresica F, Arents J, Meislich H & Turk A 1980, Fundamentals of Chemistry, 4th ed., Academic Press, New York, ISBN 0121323927
• Brown L & Holme T 2006, Chemistry for Engineering Students, Thomson Brooks/Cole, Belmont California, ISBN 0495017183
• Brown TL, LeMay HE, Bursten BE, Murphy CJ, Woodward P 2009, Chemistry: The Central Science, 11th ed., Pearson Education, Upper Saddle River, New Jersey, ISBN 9780132358484
• Brown WP c. 2007 'The Properties of Semi-Metals or Metalloids,' Doc Brown's Chemistry: Introduction to the Periodic Table, viewed 8 February 2013
• Brownlee RB, Fuller RW, Hancock WJ, Sohon MD & Whitsit JE 1943, Elements of Chemistry, Allyn and Bacon, Boston
• Brownlee RB, Fuller RT, Whitsit JE Hancock WJ & Sohon MD 1950, Elements of Chemistry, Allyn and Bacon, Boston
• Bucat RB (ed.) 1983, Elements of Chemistry: Earth, Air, Fire & Water, vol. 1, Australian Academy of Science, Canberra, ISBN 0858471132
• Büchel KH (ed.) 1983, Chemistry of Pesticides, John Wiley & Sons, New York, ISBN 0471056820
• Büchel KH, Moretto H-H, Woditsch P 2003, Industrial Inorganic Chemistry, 2nd ed., Wiley-VCH, ISBN 3527298495
• Burakowski T & Wierzchoń T 1999, Surface Engineering of Metals: Principles, Equipment, Technologies, CRC Press, Boca Raton, Florida, ISBN 0849382254
• Burrows A, Holman J, Parsons A, Pilling G & Price G 2009, Chemistry³: Introducing Inorganic, Organic and Physical Chemistry, Oxford University, Oxford, ISBN 0199277893
• Butterman WC & Carlin JF 2004, Mineral Commodity Profiles: Antimony, US Geological Survey
• Butterman WC & Jorgenson JD 2005, Mineral Commodity Profiles: Germanium, US Geological Survey
• Buzea C & Robbie K 2005, 'Assembling the Puzzle of Superconducting Elements: A Review', Superconductor Science and Technology, vol 18, no. 1, pp. R1–R8, doi:10.1088/0953-2048/18/1/R01
• Calderazzo F, Ercoli R & Natta G 1968, 'Metal Carbonyls: Preparation, Structure, and Properties', in I Wender & P Pino (eds), Organic Syntheses via Metal Carbonyls: Volume 1, Interscience Publishers, New York, pp. 1–272
• Carapella SC 1968a, 'Arsenic' in CA Hampel (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York, pp. 29–32
• Carapella SC 1968, 'Antimony' in CA Hampel (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York, pp. 22–5
• Carlin JF 2011, Minerals Year Book: Antimony, United States Geological Survey
• Carter CB & Norton MG 2013, Ceramic Materials: Science and Engineering, 2nd ed., Springer Science+Business Media, New York, ISBN 9781461435235
• Cegielski C 1998, Yearbook of Science and the Future, Encyclopædia Britannica, Chicago, ISBN 0852296576
• Chalmers B 1959, Physical Metallurgy, John Wiley & Sons, New York
• Champion J, Alliot C, Renault E, Mokili BM, Chérel M, Galland N & Montavon G 2010, 'Astatine Standard Redox Potentials and Speciation in Acidic Medium', The Journal of Physical Chemistry A, vol. 114, no. 1, pp. 576–82, doi:10.1021/jp9077008
• Chang R 2002, Chemistry, 7th ed., McGraw Hill, Boston, ISBN 0072465336
• Chao MS & Stenger VA 1964, 'Some Physical Properties of Highly Purified Bromine', Talanta, vol. 11, no. 2, pp. 271–81, doi:10.1016/0039-9140(64)80036-9
• Chatt J 1951, 'Metal and Metalloid Compounds of the Alkyl Radicals', in EH Rodd (ed.), Chemistry of Carbon Compounds: A Modern Comprehensive Treatise, vol. 1, part A, Elsevier, Amsterdam, pp. 417–58
• Chedd G 1969, Half-Way Elements: The Technology of Metalloids, Doubleday, New York
• Chizhikov DM & Shchastlivyi VP 1968, Selenium and Selenides, translated from the Russian by EM Elkin, Collet’s, London
• Chizhikov DM & Shchastlivyi 1970, Tellurium and the Tellurides, Collet's, London
• Choppin GR & Johnsen RH 1972, Introductory Chemistry, Addison-Wesley, Reading, Massachusetts
• Chung DDL 2010, Composite Materials: Science and Applications, 2nd ed., Springer-Verlag, London, ISBN 978184882830
• Clark GL 1960, The Encyclopedia of Chemistry, Reinhold, New York
• Cobb C & Fetterolf ML 2005, The Joy of Chemistry, Prometheus Books, New York, ISBN 1591022312
• Cohen ML & Chelikowsky JR 1988, Electronic Structure and Optical Properties of Semiconductors, Springer Verlag, Berlin, ISBN 3540188185
• Coles BR & Caplin AD 1976, The Electronic Structures of Solids, Edward Arnold, London, ISBN 0844808741
• Considine DM & Considine GD (eds) 1984, 'Metalloid', in Van Nostrand Reinhold Encyclopedia of Chemistry, 4th ed., Van Nostrand Reinhold, New York, ISBN 0442225725
• Cooper DG 1968, The Periodic Table, 4th ed., Butterworths, London
• Corbridge DEC 2012, Phosphorus: Chemistry, Biochemistry and Technology, 6th ed., CRC Press, Boca Raton, Florida, ISBN 9781439840887
• Corwin CH 2005, Introductory Chemistry: Concepts & Connections, 4th ed., Prentice Hall, Upper Saddle River, New Jersey, ISBN 0131448501
• Cotton FA, Wilkinson G & Gaus P 1995, Basic Inorganic Chemistry, 3rd ed., John Wiley & Sons, New York, ISBN 0471505323
• Cotton FA, Wilkinson G, Murillo CA & Bochmann 1999, Advanced Inorganic Chemistry, 6th ed., John Wiley & Sons, New York, ISBN 0471199575
• Cox PA 2004, Inorganic Chemistry, 2nd ed., Instant Notes series, Bios Scientific, London, ISBN 1859962890
• Craig PJ 2003, Organometallic Compounds in the Environment, John Wiley & Sons, New York, ISBN 0471899933
• Cusack N 1967, The Electrical and Magnetic Properties of Solids: An Introductory Textbook, 5th ed., John Wiley & Sons, New York
• Cusack N E 1987, The Physics of Structurally Disordered Matter: An Introduction, A Hilger in association with the University of Sussex Press, Bristol, ISBN 0852745915
• Daintith J (ed.) 2004, Oxford Dictionary of Chemistry, 5th ed., Oxford University, Oxford, ISBN 0199204632
• Daniel-Hoffmann M, Sredni B & Nitzan Y 2012, 'Bactericidal Activity of the Organo-Tellurium Compound AS101 Against Enterobacter Cloacae,' Journal of Antimicrobial Chemotherapy, vol. 67, no. 9, pp. 2165–72, doi:10.1093/jac/dks185
• Daub GW & Seese WS 1996, Basic Chemistry, 7th ed., Prentice Hall, New York, ISBN 013373630X
• Davidson DF & Lakin HW 1973, 'Tellurium', in DA Brobst & WP Pratt (eds), United States Mineral Resources, Geological survey professional paper 820, United States Government Printing Office, Washington, pp. 627–30
• Dávila ME, Molotov SL, Laubschat C & Asensio MC 2002, 'Structural Determination of Yb Single-Crystal Films Grown on W(110) Using Photoelectron Diffraction', Physical Review B, vol. 66, no. 3, p. 035411–18, doi:10.1103/PhysRevB.66.035411
• Demetriou MD, Launey ME, Garrett G, Schramm JP, Hofmann DC, Johnson WL & Ritchie RO 2011, 'A Damage-Tolerant Glass', Nature Materials, vol. 10, February, pp. 123–8, doi:10.1038/nmat2930
• Deming HG 1925, General Chemistry: An Elementary Survey, 2nd ed., John Wiley & Sons, New York
• Denniston KJ, Topping JJ & Caret RL 2004, General, Organic, and Biochemistry, 5th ed., McGraw-Hill, New York, ISBN 0072828471
• Deprez N & McLachan DS 1988, 'The Analysis of the Electrical Conductivity of Graphite Conductivity of Graphite Powders During Compaction', Journal of Physics D: Applied Physics, vol. 21, no. 1, doi:10.1088/0022-3727/21/1/015
• Desai PD, James HM & Ho CY 1984, 'Electrical Resistivity of Aluminum and Manganese', Journal of Physical and Chemical Reference Data, vol. 13, no. 4, pp. 1131–72, doi:10.1063/1.555725
• Desch CH 1914, Intermetallic Compounds, Longmans, Green and Co., New York
• Detty MR & O’Regan MB 1994, Tellurium-Containing Heterocycles, (The Chemistry of Heterocyclic Compounds, vol. 53), John Wiley & Sons, New York
• Dev N 2008, 'Modelling Selenium Fate and Transport in Great Salt Lake Wetlands', PhD dissertation, University of Utah, ProQuest, Ann Arbor, Michigan, ISBN 054986542X
• De Zuane J 1997, Handbook of Drinking Water Quality, 2nd ed., John Wiley & Sons, New York, ISBN 047128789X
• Divakar C, Mohan M & Singh AK 1984, 'The Kinetics of Pressure-Induced Fcc-Bcc Transformation in Ytterbium', Journal of Applied Physics, vol. 56, no. 8, pp. 2337–40, doi:10.1063/1.334270
• Donohue J 1982, The Structures of the Elements, Robert E. Krieger, Malabar, Florida, ISBN 0898742307
• Douglade J & Mercier R 1982, 'Structure Cristalline et Covalence des Liaisons dans le Sulfate d'Arsenic(III), As₂(SO₄)₃', Acta Crystallographica Section B, vol. 38, no. 3, pp. 720–3, doi:10.1107/S056774088200394X
• Du Y, Ouyang C, Shi S & Lei M 2010, 'Ab Initio Studies on Atomic and Electronic Structures of Black Phosphorus', Journal of Applied Physics, vol. 107, no. 9, pp. 093718–1–4, doi:10.1063/1.3386509
• Dunlap BD, Brodsky MB, Shenoy GK & Kalvius GM 1970, 'Hyperfine Interactions and Anisotropic Lattice Vibrations of ²³⁷Np in α-Np Metal', Physical Review B, vol. 1, no. 1, pp. 44–9, doi:10.1103/PhysRevB.1.44
• Dunstan S 1968, Principles of Chemistry, D. Van Nostrand Company, London
• Dupree R, Kirby DJ & Freyland W 1982, 'N.M.R. Study of Changes in Bonding and the Metal-Non-metal Transition in Liquid Caesium-Antimony Alloys', Philosophical Magazine Part B, vol. 46 no. 6, pp. 595–606, doi:10.1080/01418638208223546
• Eagleson M 1994, Concise Encyclopedia Chemistry, Walter de Gruyter, Berlin, ISBN 3110114518
• Eason R 2007, Pulsed Laser Deposition of Thin Films: Applications-Led Growth of Functional Materials, Wiley-Interscience, New York
• Ebbing DD & Gammon SD 2010, General Chemistry, 9th ed. enhanced, Brooks/Cole, Belmont, California, ISBN 9780618934690
• Eberle SH 1985, 'Chemical Behavior and Compounds of Astatine', pp. 183–209, in Kugler & Keller
• Edwards PP & Sienko MJ 1983, 'On the Occurrence of Metallic Character in the Periodic Table of the Elements', Journal of Chemical Education, vol. 60, no. 9, pp. 691–6, doi:10.1021ed060p691
• Edwards PP, Lodge MTJ, Hensel F & Redmer R 2010, '...A Metal Conducts and a Non-metal Doesn't', Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 368, pp. 941–65, doi:10.1098/rsta.2009.0282
• Eggins BR 1972, Chemical Structure and Reactivity, MacMillan, London, ISBN 0333081455
• Eichler R, Aksenov NV, Belozerov AV, Bozhikov GA, Chepigin VI, Dmitriev SN, Dressler R, Gäggeler HW, Gorshkov VA, Haenssler F, Itkis MG, Laube A, Lebedev VY, Malyshev ON, Oganessian YT, Petrushkin OV, Piguet D, Rasmussen P, Shishkin SV, Shutov, AV, Svirikhin AI, Tereshatov EE, Vostokin GK, Wegrzecki M & Yeremin AV 2007, 'Chemical Characterization of Element 112,' Nature, vol. 447, pp. 72–5, doi:10.1038/nature05761
• Emeleús HJ & Sharpe AG 1959, Advances in Inorganic Chemistry and Radiochemistry, vol. 1, Academic Press, New York
• Emsley J 1971, The Inorganic Chemistry of the Non-metals, Methuen Educational, London, ISBN 0423861204
• Emsley J 2001, Nature's Building Blocks: An A–Z guide to the Elements, Oxford University Press, Oxford, ISBN 0198503415
• Eranna G 2011, Metal Oxide Nanostructures as Gas Sensing Devices, Taylor & Francis, Boca Raton, Florida, ISBN 1439863407
• Evans RC 1966, An Introduction to Crystal Chemistry, Cambridge University, Cambridge
• Evans KA 1993, 'Properties and Uses of Oxides and Hydroxides,' in AJ Downs (ed.), Chemistry of Aluminium, Gallium, Indium, and Thallium, Blackie Academic & Professional, Bishopbriggs, Glasgow, pp. 248–91, ISBN 075140103X
• EVM (Expert Group on Vitamins and Minerals) 2003, Safe Upper Levels for Vitamins and Minerals, UK Food Standards Agency, London, ISBN 1904026117
• Fehlner TP 1990, 'The Metallic Face of Boron,' in AG Sykes (ed.), Advances in Inorganic Chemistry, vol. 35, Academic Press, Orlando, pp. 199–233
• Fellet M 'Redefining Hydrogen Bonds, the Givers of Life,' New Scientist, 28 July 2011, ISSN 10321233
• Feng & Jin 2005, Introduction to Condensed Matter Physics: Volume 1, World Scientific, Singapore, ISBN 1842653474
• Fernelius WC 1982, 'Polonium', Journal of Chemical Education, vol. 59, no. 9, pp. 741–2, doi:10.1021/ed059p741
• Ferro R & Saccone A 2008, Intermetallic Chemistry, Elsevier, Oxford, p. 233, ISBN 0080440991
• Fesquet AA 1872, A Practical Guide for the Manufacture of Metallic Alloys, trans. A. Guettier, Henry Carey Baird, Philadelphia
• Fine LW & Beall H 1990, Chemistry for Engineers and Scientists, Saunders College Publishing, Philadelphia, ISBN 0030215374
• Foster W 1936, The Romance of Chemistry, D Appleton-Century, New York
• Foster LS & Wrigley AN 1958, 'Periodic Table', in GL Clark, GG Hawley & WA Hamor (eds), The Encyclopedia of Chemistry (Supplement), Reinhold, New York, pp. 215–20
• Friend JN 1953, Man and the Chemical Elements, 1st ed., Charles Scribner's Sons, New York
• Fritz JS & Gjerde DT 2008, Ion Chromatography, John Wiley & Sons, New York, ISBN 3527613250
• Gary S 2013, 'Poisoned Alloy' the Metal of the Future', News in science, viewed 28 August 2013
• Geckeler S 1987, Optical Fiber Transmission Systems, Artech Hous, Norwood, Massachusetts, ISBN 0890062269
• Geman Energy Society 2008, Planning and Installing Photovoltaic Systems: A Guide for Installers, Architects and Engineers, 2nd ed., Earthscan, London, ISBN 9781844074426
• Gordh G, Gordh G & Headrick D 2003, A Dictionary of Entomology, CABI Publishing, Wallingford, ISBN 0851996558
• Gladyshev VP & Kovaleva SV 1998, 'Liquidus Shape of the Mercury–Gallium System', Russian Journal of Inorganic Chemistry, vol. 43, no. 9, pp. 1445–6
• Glazov VM, Chizhevskaya SN & Glagoleva NN 1969, Liquid Semiconductors, Plenum, New York
• Glinka N 1965, General Chemistry, trans. D Sobolev, Gordon & Breach, New York
• Glockling F 1969, The Chemistry of Germanium, Academic, London
• Glorieux B, Saboungi ML & Enderby JE 2001, 'Electronic Conduction in Liquid Boron', Europhysics Letters (EPL), vol. 56, no. 1, pp. 81–5, doi:10.1209/epl/i2001-00490-0
• Goldsmith RH 1982, 'Metalloids', Journal of Chemical Education, vol. 59, no. 6, pp. 526–7, doi:10.1021/ed059p526
• Good JM, Gregory O & Bosworth N 1813, 'Arsenicum', in Pantologia: A New Cyclopedia...of Essays, Treatises, and Systems...with a General Dictionary of Arts, Sciences, and Words..., Kearsely, London
• Goodrich BG 1844, A Glance at the Physical Sciences, Bradbury, Soden & Co., Boston
• Gray T 2009, The Elements: A Visual Exploration of Every Known Atom in the Universe, Black Dog & Leventhal, New York, ISBN 9781579128142
• Gray T 2010, 'Metalloids (7)', viewed 8 February 2013
• Gray T, Whitby M & Mann N 2011, Mohs Hardness of the Elements, viewed 12 Feb 2012
• Greaves GN, Knights JC & Davis EA 1974, 'Electronic Properties of Amorphous Arsenic', in J Stuke & W Brenig (eds), Amorphous and Liquid Semiconductors: Proceedings, vol. 1, Taylor & Francis, London, pp. 369–74, ISBN 9780470834855
• Greenwood NN 2001, 'Main Group Element Chemistry at the Millennium', Journal of the Chemical Society, Dalton Transactions, issue 14, pp. 2055–66, doi:10.1039/b103917m
• Greenwood NN & Earnshaw A 2002, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, ISBN 0750633654
• Grimes RN 2011, Carboranes, 2nd ed., Academic Press, London, ISBN 012374170X
• Guan PF, Fujita T, Hirata A, Liu YH & Chen MW 2012, 'Structural Origins of the Excellent Glass-forming Ability of Pd₄₀Ni₄₀P₂₀', Physical Review Letters, vol. 108, no. 17, pp. 175501–1–5, doi:10.1103/PhysRevLett.108.175501
• Hager T 2006, The Demon under the Microscope, Three Rivers Press, New York, ISBN 9781400082148
• Haiduc I & Zuckerman JJ 1985, Basic Organometallic Chemistry, Walter de Gruyter, Berlin, ISBN 0899250068
• Haissinsky M & Coche A 1949, 'New Experiments on the Cathodic Deposition of Radio-elements', Journal of the Chemical Society, pp. S397–400
• Haller EE 2006, 'Germanium: From its Discovery to SiGe Devices', Materials Science in Semiconductor Processing, vol. 9, nos 4–5, doi:10.1016/j.mssp.2006.08.063, viewed 8 February 2013
• Hamm DI 1969, Fundamental Concepts of Chemistry, Meredith Corporation, New York, ISBN 0390406511
• Hampel CA & Hawley GG 1966, The Encyclopedia of Chemistry, 3rd ed., Van Nostrand Reinhold, New York
• Hampel CA (ed.) 1968, The Encyclopedia of the Chemical Elements, Reinhold, New York
• Hampel CA & Hawley GG 1976, Glossary of Chemical Terms, Van Nostrand Reinhold, New York, ISBN 0442232381
• Harding C, Johnson DA & Janes R 2002, Elements of the p Block, Royal Society of Chemistry, Cambridge, ISBN 0854046909
• Hasan H 2009, The Boron Elements: Boron, Aluminum, Gallium, Indium, Thallium, The Rosen Publishing Group, New York, ISBN 1435853334
• Hatcher WH 1949, An Introduction to Chemical Science, John Wiley & Sons, New York
• Hawkes SJ 1999, 'Polonium and Astatine are not Semimetals', Chem 13 News, February, p. 14, ISSN 07031157
• Hawkes SJ 2001, 'Semimetallicity', Journal of Chemical Education, vol. 78, no. 12, pp. 1686–7, doi:10.1021/ed078p1686
• Hawkes SJ 2010, 'Polonium and Astatine are not Semimetals', Journal of Chemical Education, vol. 87, no. 8, p. 783, doi:10.1021ed100308w
• Haynes WM (ed.) 2012, CRC Handbook of Chemistry and Physics, 93rd ed., CRC Press, Boca Raton, Florida, ISBN 1439880492
• Hein M, Best LR, Pattison S & Arena S 2004, 8th ed., Introduction to General, Organic, and Biochemistry, John Wiley & Sons, Hoboken, New Jersey, ISBN 0471451967
• Henderson M 2000, Main Group Chemistry, The Royal Society of Chemistry, Cambridge, ISBN 0854046178
• Hermann A, Hoffmann R & Ashcroft NW 2013, 'Condensed Astatine: Monatomic and Metallic', Physical Review Letters, vol. 111, pp. 11604–1−11604-5, doi:10.1103/PhysRevLett.111.116404
• Hérold A 2006, 'An Arrangement of the Chemical Elements in Several Classes Inside the Periodic Table According to their Common Properties', Comptes Rendus Chimie, vol. 9, no. 1, pp. 148–53, doi:10.1016/j.crci.2005.10.002
• Hill G & Holman J 2000, Chemistry in Context, 5th ed., Nelson Thornes, Cheltenham, ISBN 0174483074
• Hiller LA & Herber RH 1960, Principles of Chemistry, McGraw-Hill, New York
• Hindman JC 1968, 'Neptunium', in CA Hampel (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York, pp. 432–7
• Hoddeson L 2007, 'In the Wake of Thomas Kuhn's Theory of Scientific Revolutions: The Perspective of an Historian of Science,' in S Vosniadou, A Baltas & X Vamvakoussi (eds), Reframing the Conceptual Change Approach in Learning and Instruction, Elsevier, Amsterdam, pp. 25–34, ISBN 9780080453552
• Holt, Rinehart & Wilson c. 2007 'Why Polonium and Astatine are not Metalloids in HRW texts', viewed 8 February 2013
• Hopkins BS & Bailar JC 1956, General Chemistry for Colleges, 5th ed., D. C. Heath, Boston
• Horvath 1973, 'Critical Temperature of Elements and the Periodic System', Journal of Chemical Education, vol. 50, no. 5, pp. 335–6, doi:10.1021/ed050p335
• Houghton RP 1979, Metal Complexes in Organic Chemistry, Cambridge University Press, Cambridge, ISBN 0521219922
• House JE 2008, Inorganic Chemistry, Academic Press (Elsevier), Burlington, Massachusetts, ISBN 0123567866
• House JE & House KA 2010, Descriptive Inorganic Chemistry, 2nd ed., Academic Press, Burlington, Massachusetts, ISBN 012088755X
• Housecroft CE & Sharpe AG 2008, Inorganic Chemistry, 3rd ed., Pearson Education, Harlow, ISBN 9780131755536
• Hultgren HH 1966, 'Metalloids', in GL Clark & GG Hawley (eds), The Encyclopedia of Inorganic Chemistry, 2nd ed., Reinhold Publishing, New York
• Hunt A 2000, The Complete A-Z Chemistry Handbook, 2nd ed., Hodder & Stoughton, London, ISBN 0340772182
• Iler RK 1979, The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties, and Biochemistry, John Wiley, New York, ISBN 9780471024040
• Inagaki M 2000, New Carbons: Control of Structure and Functions, Elsevier, Oxford, ISBN 0080437133
• Isbell C 1998, 'Copper', in F Habashi (ed.), Alloys: Preparation, Properties, Applications, Wiley-VCH, Weinheim, pp. 65–108, ISBN 3527295917
• IUPAC 1959, Nomenclature of Inorganic Chemistry, 1st ed., Butterworths, London
• IUPAC 1971, Nomenclature of Inorganic Chemistry, 2nd ed., Butterworths, London, ISBN 0408701684
• IUPAC 2005, Nomenclature of Inorganic Chemistry (the "Red Book"), NG Connelly & T Damhus eds, RSC Publishing, Cambridge, ISBN 0854044388
• IUPAC 2006–, Compendium of Chemical Terminology (the "Gold Book"), 2nd ed., by M Nic, J Jirat & B Kosata, with updates compiled by A Jenkins, ISBN 0967855098, doi:10.1351/goldbook
• James M, Stokes R, Ng W & Moloney J 2000, Chemical Connections 2: VCE Chemistry Units 3 & 4, John Wiley & Sons, Milton, Queensland, ISBN 0701634383
• Jaouen G & Gibaud S 2010, 'Arsenic-based Drugs: From Fowler's solution to Modern Anticancer Chemotherapy', Medicinal Organometallic Chemistry, vol. 32, pp. 1–20, doi:10.1007/978-3-642-13185-1_1
• Jaskula BW 2013, Mineral Commodity Profiles: Gallium, US Geological Survey
• Jenkins GM & Kawamura K 1976, Polymeric Carbons—Carbon Fibre, Glass and Char, Cambridge University Press, Cambridge, ISBN 0521206936
• Jezequel G & Thomas J 1997, 'Experimental Band Structure of Semimetal Bismuth', Physical Review B, vol. 56, no. 11, pp. 6620–6, doi:10.1103/PhysRevB.56.6620
• Johansen G & Mackintosh AR 1970, 'Electronic Structure and Phase Transitions in Ytterbium', Solid State Communications, vol. 8, no. 2, pp. 121–4
• Johnston FJ 1992, 'Metalloid' in McGraw-Hill Encyclopedia of Science & Technology, 7th ed., vol. 11, McGraw-Hill, New York, ISBN 0079092063 (set)
• Jolly WL 1966, The Chemistry of the Non-metals, Prentice-Hall, Englewood Cliffs, New Jersey
• Jones BW 2010, Pluto: Sentinel of the Outer Solar System, Cambridge University, Cambridge, ISBN 9780521194365
• Kaminow IP & Li T 2002 (eds), Optical Fiber Telecommunications, Volume IVA, Academic Press, San Diego, ISBN 0123951720
• Karabulut M, Melnik E, Stefan R, Marasinghe GK, Ray CS, Kurkjian CR & Day DE 2001, 'Mechanical and Structural Properties of Phosphate Glasses', Journal of Non-Crystalline Solids, vol. 288, nos. 1–3, pp. 8–17, doi:10.1016/S0022-3093(01)00615-9
• Kaye GWC & Laby TH 1973, Tables of Physical and Chemical Constants, 14th ed., Longman, London, ISBN 0582463262
• Keall JHH, Martin NH & Tunbridge RE 1946, 'A Report of Three Cases of Accidental Poisoning by Sodium Tellurite', British Journal of Industrial Medicine, vol. 3, no. 3, pp. 175–6
• Keller C 1985, 'Preface', in Kugler & Keller
• Kelter P, Mosher M & Scott A 2009, Chemistry: the Practical Science, Houghton Mifflin, Boston, ISBN 0547053932
• Kent W 1950, Kent's Mechanical Engineers' Handbook, 12th ed., vol. 1, John Wiley & Sons, New York
• King EL 1979, Chemistry, Painter Hopkins, Sausalito, California, ISBN 0052507262
• King RB 1994, 'Antimony: Inorganic Chemistry', in RB King (ed), Encyclopedia of Inorganic Chemistry, John Wiley, Chichester, pp. 170–5, ISBN 0471936200
• King RB 2004, 'The Metallurgist's Periodic Table and the Zintl-Klemm Concept', in DH Rouvray & RB King (eds), The Periodic Table: Into the 21st Century, Research Studies Press, Baldock, Hertfordshire, pp. 191–206, ISBN 0863802923
• Kitaĭgorodskiĭ AI 1961, Organic Chemical Crystallography, Consultants Bureau, New York
• Kleinberg J, Argersinger WJ & Griswold E 1960, Inorganic Chemistry, DC Health, Boston
• Klement W, Willens RH & Duwez P 1960, 'Non-Crystalline Structure in Solidified Gold–Silicon Alloys', Nature, vol. 187, pp. 869–70, doi|10.1038/187869b0
• Klemm W 1950, 'Einige Probleme aus der Physik und der Chemie der Halbmetalle und der Metametalle', Angewandte Chemie, vol. 62, no. 6, pp. 133–42
• Klug HP & Brasted RC 1958, Comprehensive Inorganic Chemistry: The Elements and Compounds of Group IV A, Van Nostrand, New York
• Kneen WR, Rogers MJW & Simpson P 1972, Chemistry: Facts, Patterns, and Principles, Addison-Wesley, London, ISBN 0201037793
• Kolobov AV & Tominaga J 2012, Chalcogenides: Metastability and Phase Change Phenomena, Springer-Verlag, Heidelberg, ISBN 9783642287053
• Kopp JG, Lipták BG & Eren H 000, 'Magnetic Flowmeters', in BG Lipták (ed.), Instrument Engineers' Handbook, 4th ed., vol. 1, Process Measurement and Analysis, CRC Press, Boca Raton, Florida, pp. 208–224, ISBN 0849310830
• Korenman IM 1959, 'Regularities in Properties of Thallium', Journal of General Chemistry of the USSR, English translation, Consultants Bureau, New York, vol. 29, no. 2, pp. 1366–90, ISSN 00221279
• Kotz JC, Treichel P & Weaver GC 2009, Chemistry and Chemical Reactivity, 7th ed., Brooks/Cole, Belmont, California, ISBN 1439041318
• Kozyrev PT 1959, 'Deoxidized Selenium and the Dependence of its Electrical Conductivity on Pressure. II', Physics of the Solid State, translation of the journal Solid State Physics (Fizika tverdogo tela) of the Academy of Sciences of the USSR, vol. 1, pp. 102–10
• Kraig RE, Roundy D & Cohen ML 2004, 'A Study of the Mechanical and Structural Properties of Polonium', Solid State Communications, vol. 129, issue 6, Feb, pp. 411–13, doi:10.1016/j.ssc.2003.08.001
• Krannich LK & Watkins CL 2006, 'Arsenic: Organoarsenic chemistry,' Encyclopedia of inorganic chemistry, viewed 12 Feb 2012
• Kreith F & Goswami DY (eds) 2005, The CRC Handbook of Mechanical Engineering, 2nd ed., Boca Raton, Florida, ISBN 0849308666
• Krishnan S, Ansell S, Felten J, Volin K & Price D 1998, 'Structure of Liquid Boron', Physical Review Letters, vol. 81, no. 3, pp. 586–9, doi:10.1103/PhysRevLett.81.586
• Kudryavtsev AA 1974, The Chemistry & Technology of Selenium and Tellurium, translated from the 2nd Russian edition and revised by EM Elkin, Collet's, London, ISBN 0569080096
• Kugler HK & Keller C (eds) 1985, Gmelin Handbook of Inorganic and Organometallic chemistry, 8th ed., 'At, Astatine', system no. 8a, Springer-Verlag, Berlin, ISBN 3540935169
• Lagrenaudie J 1953, 'Semiconductive Properties of Boron' (in French), Journal de Chimie Physique, vol. 50, nos. 11–12, Nov–Dec, pp. 629–33, ISSN 00217689
• Le Bras M, Wilkie CA & Bourbigot S (eds) 2005, Fire Retardancy of Polymers: New Applications of Mineral Fillers, Royal Society of Chemistry, Cambridge, ISBN 0854045821
• Lehto Y & Hou X 2011, Chemistry and Analysis of Radionuclides: Laboratory Techniques and Methodology, Wiley-VCH, Weinheim, ISBN 9783527326587
• Lewis RJ 1993, Hawley's Condensed Chemical Dictionary, 12th ed., Van Nostrand Reinhold, New York, ISBN 0442011318
• Li XP 1990, 'Properties of Liquid Arsenic: A Theoretical Study', Physical Review B, vol. 41, no. 12, pp. 8392–406, doi:10.1103/PhysRevB.41.8392
• Locke EG, Baechler RH, Beglinger E, Bruce HD, Drow JT, Johnson KG, Laughnan DG, Paul BH, Rietz RC, Saeman JF & Tarkow H 1956, 'Wood', in RE Kirk & DF Othmer (eds), Encyclopedia of Chemical Technology, vol. 15, The Interscience Encyclopedia, New York, pp. 72–102
• Löffler JF, Kündig AA & Dalla Torre FH 2007, 'Rapid Solidification and Bulk Metallic Glasses—Processing and Properties,' in JR Groza, JF Shackelford, EJ Lavernia EJ & MT Powers (eds), Materials Processing Handbook, CRC Press, Boca Raton, Florida, pp. 17–1–44, ISBN 0849332168
• Long GG & Hentz FC 1986, Problem Exercises for General Chemistry, 3rd ed., John Wiley & Sons, New York, ISBN 0471828408
• Lovett DR 1977, Semimetals & Narrow-Bandgap Semi-conductors, Pion, London, ISBN 0850860601
• Lutz J, Schlangenotto H, Scheuermann U, De Doncker R 2011, Semiconductor Power Devices: Physics, Characteristics, Reliability, Springer-Verlag, Berlin, ISBN 3642111246
• MacKay KM, MacKay RA & Henderson W 2002, Introduction to Modern Inorganic Chemistry, 6th ed., Nelson Thornes, Cheltenham, ISBN 0748764208
• Madelung O 2004, Semiconductors: Data Handbook, 3rd ed., Springer-Verlag, Berlin, ISBN 9783540404880
• Maeder T 2013, 'Review of Bi₂O₃ Based Glasses for Electronics and Related Applications, International Materials Reviews, vol. 58, no. 1, pp. 3‒40, doi:10.1179/1743280412Y.0000000010
• Mahan BH 1965, University Chemistry, Addison-Wesley, Reading, Massachusetts
• Malerba F 1985, The Semiconductor Business: The Economics of Rapid Growth and Decline, Frances Pinter, London, ISBN 0861875427
• Manahan SE 2001, Fundamentals of Environmental Chemistry, 2nd ed., CRC Press, Boca Raton, Florida, ISBN 156670491X
• Mann JB, Meek TL & Allen LC 2000, 'Configuration Energies of the Main Group Elements', Journal of the American Chemical Society, vol. 122, no. 12, pp. 2780–3, doi:10.1021ja992866e
• Marezio M & Licci F 2000, 'Strategies for Tailoring New Superconducting Systems', in X Obradors, F Sandiumenge & J Fontcuberta (eds), Applied Superconductivity 1999: Large scale applications, volume 1 of Applied Superconductivity 1999: Proceedings of EUCAS 1999, the Fourth European Conference on Applied Superconductivity, held in Sitges, Spain, 14–17 September 1999, Institute of Physics, Bristol, pp. 11–16, ISBN 0750307455
• Marković N, Christiansen C & Goldman AM 1998, 'Thickness-Magnetic Field Phase Diagram at the Superconductor-Insulator Transition in 2D', Physical Review Letters, vol. 81, no. 23, pp. 5217–20, doi:10.1103/PhysRevLett.81.5217
• Massey AG 2000, Main Group Chemistry, 2nd ed., John Wiley & Sons, Chichester, ISBN 0471490393
• Masters GM & Ela W 2008, Introduction to Environmental Engineering and Science, 3rd ed., Prentice Hall, Upper Saddle River, New Jersey, ISBN 9780131481930
• Masterton WL & Slowinski EJ 1977, Chemical Principles, 4th ed., W. B. Saunders, Philadelphia, ISBN 0721661734
• Matula RA 1979, 'Electrical Resistivity of Copper, Gold, Palladium, and Silver,' Journal of Physical and Chemical Reference Data, vol. 8, no. 4, pp. 1147–298, doi:10.1063/1.555614
• McMurray J & Fay RC 2009, General Chemistry: Atoms First, Prentice Hall, Upper Saddle River, New Jersey, ISBN 0321571630
• McQuarrie DA & Rock PA 1987, General Chemistry, 3rd ed., WH Freeman, New York, ISBN 0716721694
• Mellor JW 1964, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. 9, John Wiley, New York
• Mellor JW 1964, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. 11, John Wiley, New York
• Mendeléeff DI 1897, The Principles of Chemistry, vol. 2, 5th ed., trans. G Kamensky, AJ Greenaway (ed.), Longmans, Green & Co., London
• Meskers CEM, Hagelüken C & Van Damme G 2009, 'Green Recycling of EEE: Special and Precious Metal EEE', in SM Howard, P Anyalebechi & L Zhang (eds), Proceedings of Sessions and Symposia Sponsored by the Extraction and Processing Division (EPD) of The Minerals, Metals and Materials Society (TMS), held during the TMS 2009 Annual Meeting & Exhibition San Francisco, California, February 15–19, 2009, The Minerals, Metals and Materials Society, Warrendale, Pennsylvania, ISBN 9780873397322, pp. 1131–6
• Metcalfe HC, Williams JE & Castka JF 1974, Modern Chemistry, Holt, Rinehart and Winston, New York, ISBN 0030894506
• Meyer JS, Adams WJ, Brix KV, Luoma SM, Mount DR, Stubblefield WA & Wood CM (eds) 2005, Toxicity of Dietborne Metals to Aquatic Organisms, Proceedings from the Pellston Workshop on Toxicity of Dietborne Metals to Aquatic Organisms, 27 July–1 August 2002, Fairmont Hot Springs, British Columbia, Canada, Society of Environmental Toxicology and Chemistry, Pensacola, Florida, ISBN 1880611708
• Mhiaoui S, Sar F, Gasser J 2003, 'Influence of the History of a Melt on the Electrical Resistivity of Cadmium–Antimony Liquid Alloys', Intermetallics, vol. 11, nos 11–12, pp. 1377–82, doi:10.1016/j.intermet.2003.09.008
• Miller GJ, Lee C & Choe W 2002, 'Structure and Bonding Around the Zintl border', in G Meyer, D Naumann & L Wesermann (eds), Inorganic chemistry highlights, Wiley-VCH, Weinheim, pp. 21–53, ISBN 3527302654
• Millot F, Rifflet JC, Sarou-Kanian V & Wille G 2002, 'High-Temperature Properties of Liquid Boron from Contactless Techniques', International Journal of Thermophysics, vol. 23, no. 5, pp. 1185–95, doi:10.1023/A:1019836102776
• Mingos DMP 1998, Essential Trends in Inorganic Chemistry, Oxford University, Oxford, ISBN 0198501080
• Moeller T 1954, Inorganic Chemistry: An Advanced Textbook, John Wiley & Sons, New York
• Molina-Quiroz RC, Muñoz-Villagrán CM, de la Torre E, Tantaleán JC, Vásquez CC & Pérez-Donoso JM 2012, 'Enhancing the Antibiotic Antibacterial Effect by Sub Lethal Tellurite Concentrations: Tellurite and Cefotaxime Act Synergistically in Escherichia Coli', PloS (Public Library of Science) ONE, vol. 7, no. 4, doi:10.1371/journal.pone.0035452
• Moody B 1991, Comparative Inorganic Chemistry, 3rd ed., Edward Arnold, London, ISBN 0713136790
• Moore LJ, Fassett JD, Travis JC, Lucatorto TB & Clark CW 1985, 'Resonance-Ionization Mass Spectrometry of Carbon', Journal of the Optical Society of America B, vol. 2, no. 9, pp. 1561–5, doi:10.1364/JOSAB.2.001561
• Moore JT 2011, Chemistry for Dummies, 2nd ed., John Wiley & Sons, New York, ISBN 1118092929
• Morgan WC 1906, Qualitative Analysis as a Laboratory Basis for the Study of General Inorganic Chemistry, The Macmillan Company, New York
• Morita A 1986, 'Semiconducting Black Phosphorus', Journal of Applied Physics A, vol. 39, no. 4, pp. 227–42, doi:10.1007/BF00617267
• Moss TS 1952, Photoconductivity in the Elements, London, Butterworths
• Murray JF 1928, 'Cable-Sheath Corrosion', Electrical World, vol. 92, Dec 29, pp. 1295–7, ISSN 00134457
• Nagao T, Sadowski1 JT, Saito M, Yaginuma S, Fujikawa Y, Kogure T, Ohno T, Hasegawa Y, Hasegawa S & Sakurai T 2004, 'Nanofilm Allotrope and Phase Transformation of Ultrathin Bi Film on Si(111)-7×7', Physical Review Letters, vol. 93, no. 10, pp. 105501–1–4, doi:10.1103/PhysRevLett.93.105501
• Nemodruk AA & Karalova ZK 1969, Analytical Chemistry of Boron, R Kondor trans., Ann Arbor Humphrey Science, Ann Arbor, Michigan
• Neuburger MC 1936, 'Gitterkonstanten für das Jahr 1936' (in German), Zeitschrift für Kristallographie, vol. 93, pp. 1–36, ISSN 00442968
• Nickelès J 1861, 'On a New Characteristic of the So-Called Semi-Metals', American Journal of Science, vol. 82, ISSN 00029599
• Nickless G 1968, Inorganic Sulphur Chemistry, Elsevier, Amsterdam
• Nielsen FH 1998, 'Ultratrace Elements in Nutrition: Current Knowledge and Speculation', The Journal of Trace Elements in Experimental Medicine, vol. 11, pp. 251–74, doi:10.1002/(SICI)1520-670X(1998)11:2/3<251::AID-JTRA15>3.0.CO;2-Q
• NIST (National Institute of Standards and Technology) 2010, Ground Levels and Ionization Energies for Neutral Atoms, by WC Martin, A Musgrove, S Kotochigova & JE Sansonetti, viewed 8 February 2013
• National Research Council 1984, The Competitive Status of the U.S. Electronics Industry: A Study of the Influences of Technology in Determining International Industrial Competitive Advantage, National Academy Press, Washington, DC, ISBN 0309033977
• New Scientist 1975, 'Chemistry on the Islands of Stability', 11 Sep, p. 574, ISSN 10321233
• Oderberg DS 2007, Real Essentialism, Routledge, New York, ISBN 1134348851
• Oxford English Dictionary 1989, 2nd ed., Oxford University, Oxford, ISBN 0198612133
• Oganov AR, Chen J, Gatti C, Ma Y, Ma Y, Glass CW, Liu Z, Yu T, Kurakevych OO & Solozhenko VL 2009, 'Ionic High-Pressure Form of Elemental Boron', Nature, vol. 457, 12 Feb, pp. 863–8, doi:10.1038/nature07736
• Oganov AR 2010, 'Boron Under Pressure: Phase Diagram and Novel High Pressure Phase,' in N Ortovoskaya N & L Mykola L (eds), Boron Rich Solids: Sensors, Ultra High Temperature Ceramics, Thermoelectrics, Armor, Springer, Dordrecht, pp. 207–25, ISBN 9048198232
• Ogata S, Li J & Yip S 2002, 'Ideal Pure Shear Strength of Aluminium and Copper', Science, vol. 298, no. 5594, 25 October, pp. 807–10, doi:10.1126/science.1076652
• Okakjima Y & Shomoji M 1972, Viscosity of Dilute Amalgams', Transactions of the Japan Institute of Metals, vol. 13, no. 4, pp. 255–8, ISSN 00214434
• Oldfield JE, Allaway WH, HA Laitinen, HW Lakin & OH Muth 1974, 'Tellurium', in Geochemistry and the Environment, Volume 1: The Relation of Selected Trace Elements to Health and Disease, US National Committee for Geochemistry, Subcommittee on the Geochemical Environment in Relation to Health and Disease, National Academy of Sciences, Washington, ISBN 0309022231
• Olechna DJ & Knox RS 1965, 'Energy-Band Structure of Selenium Chains', Physical Review, vol. 140, no. 3A, pp. A986–93, doi:10.1103/PhysRev.140.A986
• Oliwenstein L 2011, 'Caltech-Led Team Creates Damage-Tolerant Metallic Glass', California Institute of Technology, 12 January, viewed 8 February 2013
• Olmsted J & Williams GM 1997, Chemistry, the Molecular Science, 2nd ed., Wm C Brown, Dubuque, Iowa, ISBN 0815184506
• Orton JW 2004, The Story of Semiconductors, Oxford University, Oxford, ISBN 0198530838
• Oxtoby DW, Gillis HP & Campion A 2008, Principles of Modern Chemistry, 6th ed., Thomson Brooks/Cole, Belmont, California, ISBN 0534493661
• Parise JB, Tan K, Norby P, Ko Y & Cahill C 1996, 'Examples of Hydrothermal Titration and Real Time X-ray Diffraction in the Synthesis of Open Frameworks', MRS Proceedings, vol. 453, pp. 103–14, doi:10.1557/PROC-453-103
• Parish RV 1977, The Metallic Elements, Longman, London, ISBN 0582442788
• Parkes GD & Mellor JW 1943, Mellor's Nodern Inorganic Chemistry, Longmans, Green and Co., London
• Parry RW, Steiner LE, Tellefsen RL & Dietz PM 1970, Chemistry: Experimental Foundations, Prentice-Hall/Martin Educational, Sydney, ISBN 0725301007
• Partington 1944, A Text-book of Inorganic Chemistry, 5th ed., Macmillan, London
• Partington JR 1964, A History of Chemistry, vol. 4, Macmillan, London
• Pashaey BP & Seleznev VV 1973, 'Magnetic Susceptibility of Gallium-Indium Alloys in Liquid State', Russian Physics Journal, vol. 16, no. 4, pp. 565–6, doi:10.1007/BF00890855
• Patel MR 2012, Introduction to Electrical Power and Power Electronics CRC Press, Boca Raton, ISBN 9781466556607
• Pauling L 1988, General Chemistry, Dover Publications, New York, ISBN 0486656225
• Pearson WB 1972, The Crystal Chemistry and Physics of Metals and Alloys, Wiley-Interscience, New York, ISBN 0471675407
• Peryea FJ 1998, 'Historical Use of Lead Arsenate Insecticides, Resulting Soil Contamination and Implications for Soil Remediation, Proceedings', 16th World Congress of Soil Science, Montpellier, France, 20–26 August
• Phillips CSG & Williams RJP 1965, Inorganic Chemistry, I: Principles and Non-metals, Clarendon Press, Oxford
• Pinkerton J 1800, Petralogy. A Treatise on Rocks, vol. 2, White, Cochrane, and Co., London
• Poltavtsev YG 1974, 'X-ray Diffraction Studies on Changes in the Nature of the Interatomic Bond and Close Range Order Structure During Melting of A^IVB^VI and A^IIIB^VC^VIII Semiconductors,' Proceedings of all-union conference on chemical bond in semiconductors and submetals (in Russian), Nauka, Minsk
• Poojary DM, Borade RB & Clearfield A 1993, 'Structural Characterization of Silicon Orthophosphate', Inorganica Chimica Acta, vol. 208, no. 1, pp. 23–9, doi:10.1016/S0020-1693(00)82879-0
• Pourbaix M 1974, Atlas of Electrochemical Equilibria in Aqueous Solutions, 2nd English edition, National Association of Corrosion Engineers, Houston, ISBN 0915567989
• Powell P 1988, Principles of Organometallic Chemistry, Chapman and Hall, London, ISBN 041242830X
• Prakash GKS & Schleyer PvR (eds) 1997, Stable Carbocation Chemistry, John Wiley & Sons, New York, ISBN 0471594628
• Prudenziati M 1977, IV. 'Characterization of Localized States in β-Rhombohedral Boron', in VI Matkovich (ed.), Boron and Refractory Borides, Springer-Verlag, Berlin, pp. 241–61, ISBN 038708181X
• Puddephatt RJ & Monaghan PK 1989, The Periodic Table of the Elements, 2nd ed., Oxford University, Oxford, ISBN 0198555164
• Pyykkö P 2012, 'Relativistic Effects in Chemistry: More Common Than You Thought', Annual Review of Physical Chemistry, vol. 63, pp. 45‒64 (56), doi:10.1146/annurev-physchem-032511-143755
• Rao CNR & Ganguly P 1986, 'A New Criterion for the Metallicity of Elements', Solid State Communications, vol. 57, no. 1, pp. 5–6, doi:10.1016/0038-1098(86)90659-9
• Rao KY 2002, Structural Chemistry of Glasses, Elsevier, Oxford, ISBN 0080439586
• Rausch MD 1960, 'Cyclopentadienyl Compounds of Metals and Metalloids', Journal of Chemical Education, vol. 37, no. 11, pp. 568–78, doi:10.1021/ed037p568
• Rayner-Canham G & Overton T 2006, Descriptive Inorganic Chemistry, 4th ed., WH Freeman, New York, ISBN 0716789639
• Rayner-Canham G 2011, 'Isodiagonality in the Periodic Table', Foundations of chemistry, vol. 13, no. 2, pp. 121–9, doi:10.1007/s10698-011-9108-y
• Reardon M 2005, 'IBM Doubles Speed of Germanium chips', CNET News, August 4, viewed 27 December 2013
• Regnault MV 1853, Elements of Chemistry, vol. 1, 2nd ed., Clark & Hesser, Philadelphia
• Reilly C 2002, Metal Contamination of Food, Blackwell Science, Oxford, ISBN 0632059273
• Reilly 2004, The Nutritional Trace Metals, Blackwell, Oxford, ISBN 1405110406
• Remy H 1956, Treatise on Inorganic Chemistry, vol. II, Elsevier, Amsterdam
• Restrepo G, Mesa H, Llanos EJ & Villaveces JL 2004, 'Topological Study of the Periodic System', Journal of Chemical Information and Modelling, vol. 44, no. 1, pp. 68–75, doi:10.1021/ci034217z
• Restrepo G, Llanos EJ & Mesa H 2006, 'Topological Space of the Chemical Elements and its Properties', Journal of Mathematical Chemistry, vol. 39, no. 2, pp. 401–16, doi:10.1007/s10910-005-9041-1
• Řezanka T & Sigler K 2008, 'Biologically Active Compounds of Semi-Metals', Studies in Natural Products Chemistry, vol. 35, pp. 585–606, doi:10.1016/S1572-5995(08)80018-X
• Rochow EG 1957, The Chemistry of Organometallic Compounds, John Wiley & Sons, New York
• Rochow EG 1966, The Metalloids, DC Heath and Company, Boston
• Rochow EG 1973, 'Silicon', in JC Bailar, HJ Emeléus, R Nyholm & AF Trotman-Dickenson (eds), Comprehensive Inorganic Chemistry, vol. 1, Pergamon, Oxford, pp. 1323–1467, ISBN 008015655X
• Rochow EG 1977, Modern Descriptive Chemistry, Saunders, Philadelphia, ISBN 0721676286
• Roher GS 2001, Structure and Bonding in Crystalline Materials, Cambridge University Press, Cambridge, ISBN 0521663792
• Rossler K 1985, 'Handling of Astatine', pp. 140–56, in Kugler & Keller
• Rothenberg GB 1976, Glass Technology, Recent Developments, Noyes Data Corporation, Park Ridge, New Jersey, ISBN 0815506090
• Rouvray DH 1995, 'That Fuzzy Feeling in Chemistry', Chemistry in Britain, vol. 31, no. 71, pp. 544–6
• Roza G 2009, Bromine, Rosen Publishing, New York, ISBN 1435850688
• Russell AM & Lee KL 2005, Structure-Property Relations in Nonferrous Metals, Wiley-Interscience, New York, ISBN 047164952X
• Sacks O 2001, Uncle Tungsten: Memories of a Chemical Boyhood, Alfred A. Knopf, New York, ISBN 0375704043
• Salentine CG 1987, 'Synthesis, Characterization, and Crystal Structure of a New Potassium Borate, KB₃O₅•3H₂O', Inorganic Chemistry, vol. 26, no. 1, pp. 128–32, doi:10.1021/ic00248a025
• Samsonov GV 1968, Handbook of the Physiochemical Properties of the Elements, I F I/Plenum, New York
• Sanderson RT 1960, Chemical Periodicity, Reinhold Publishing, New York
• Savvatimskiy AI 2005, 'Measurements of the Melting Point of Graphite and the Properties of Liquid Carbon (a review for 1963–2003)', Carbon, vol. 43, no. 6, pp. 1115–42, doi:10.1016/j.carbon.2004.12.027
• Savvatimskiy AI 2009, 'Experimental Electrical Resistivity of Liquid Carbon in the Temperature Range from 4800 to ~20,000 K', Carbon, vol. 47, no. 10, pp. 2322–8, doi:10.1016/j.carbon.2009.04.009
• Schaefer JC 1968, 'Boron' in CA Hampel (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York, pp. 73–81
• Schauss AG 1991, 'Nephrotoxicity and Neurotoxicity in Humans from Organogermanium Compounds and Germanium Dioxide', Biological Trace Element Research, vol. 29, no. 3, pp. 267–80, doi:10.1007/BF03032683
• Schmidbaur H & Schier A 2008, 'A Briefing on Aurophilicity,' Chemical Society Reviews, vol. 37, pp. 1931–51, doi:10.1039/B708845K
• Schroers J 2013, 'Bulk Metallic Glasses', Physics Today, vol. 66, no. 2, pp. 32–7, doi:10.1063/PT.3.1885
• Schwartz MM 2002, Encyclopedia of Materials, Parts, and Finishes, 2nd ed., CRC Press, Boca Raton, Florida, ISBN 1566766613
• Schwietzer GK and Pesterfield LL 2010, The Aqueous Chemistry of the Elements, Oxford University, Oxford, ISBN 019539335X
• ScienceDaily 2012, 'Recharge Your Cell Phone With a Touch? New nanotechnology converts body heat into power', February 22, viewed 13 Jan 2013
• Scott EC & Kanda FA 1962, The Nature of Atoms and Molecules: A General Chemistry, Harper & Row, New York
• Secrist JH & Powers WH 1966, General Chemistry, D. Van Nostrand, Princeton, New Jersey
• Segal BG 1989, Chemistry: Experiment and Theory, 2nd ed., John Wiley & Sons, New York, ISBN 0471849294
• Sekhon BS 2012, 'Metalloid Compounds as Drugs', Research in Pharmaceutical Sciences, vol. 8, no. 3, pp. 145–58, ISSN 17359414
• Sequeira CAC 2011, 'Copper and Copper Alloys', in R Winston Revie (ed.), Uhlig's Corrosion Handbook, 3rd ed., John Wiley & Sons, Hoboken, New Jersey, pp. 757–86, ISBN 111811003X
• Seybolt AU & Burke JE 1953, Procedures in Experimental Metallurgy, John Wiley & Sons, New York
• Sharp DWA 1981, 'Metalloids', in Miall's Dictionary of Chemistry, 5th ed, Longman, Harlow, ISBN 0582351529
• Sharp DWA 1983, The Penguin Dictionary of Chemistry, 2nd ed., Harmondsworth, Middlesex, ISBN 014051113X
• Sherman E & Weston GJ 1966, Chemistry of the Non-metallic Elements, Pergamon Press, New York
• Sidgwick NV 1950, The Chemical Elements and Their Compounds, vol. 1, Clarendon, Oxford
• Siebring BR 1967, Chemistry, MacMillan, New York
• Siekierski S & Burgess J 2002, Concise Chemistry of the Elements, Horwood, Chichester, ISBN 1898563713
• Silberberg MS 2006, Chemistry: The Molecular Nature of Matter and Change, 4th ed., McGraw-Hill, New York, ISBN 0071116583
• Simple Memory Art c. 2005, Periodic Table, EVA vinyl shower curtain, San Francisco
• Slade S 2006, Elements and the Periodic Table, The Rosen Publishing Group, New York, ISBN 1404221654
• Science Learning Hub 2009, 'The Essential Elements', The University of Waikato, viewed 16 January 2013
• Smith DW 1990, Inorganic Substances: A Prelude to the Study of Descriptive Inorganic Chemistry, Cambridge University, Cambridge, ISBN 0521337380
• Smith R 1994, Conquering Chemistry, 2nd ed., McGraw-Hill, Sydney, ISBN 0074701460
• Snyder MK 1966, Chemistry: Structure and Reactions, Holt, Rinehart and Winston, New York
• Soverna S 2004, 'Indication for a Gaseous Element 112', in U Grundinger (ed.), GSI Scientific Report 2003, GSI Report 2004-1, p. 187, ISSN 01740814
• Steele D 1966, The Chemistry of the Metallic Elements, Pergamon Press, Oxford
• Stein L 1985, 'New Evidence that Radon is a Metalloid Element: Ion-Exchange Reactions of Cationic Radon', Journal of the Chemical Society, Chemical Communications, vol. 22, pp. 1631–2, doi:10.1039/C39850001631
• Stein L 1987, 'Chemical Properties of Radon' in PK Hopke (ed.) 1987, Radon and its Decay products: Occurrence, Properties, and Health Effects, American Chemical Society, Washington DC, pp. 240–51, ISBN 0841210152
• Steudel R 1977, Chemistry of the Non-metals: With an Introduction to atomic Structure and Chemical Bonding, Walter de Gruyter, Berlin, ISBN 3110048825
• Steurer W 2007, 'Crystal Structures of the Elements' in JW Marin (ed.), Concise Encyclopedia of the Structure of Materials, Elsevier, Oxford, pp. 127–45, ISBN 0080451276
• Stevens SD & Klarner A 1990, Deadly Doses: A Writer's Guide to Poisons, Writer's Digest Books, Cincinnati, Ohio, ISBN 0898793718
• Stoker HS 2010, General, Organic, and Biological Chemistry, 5th ed., Brooks/Cole, Cengage Learning, Belmont California, ISBN 0495831468
• Stott RW 1956, A Companion to Physical and Inorganic Chemistry, Longmans, Green and Co., London
• Stuke J 1974, 'Optical and Electrical Properties of Selenium', in RA Zingaro & WC Cooper (eds), Selenium, Van Nostrand Reinhold, New York, pp. 174–297, ISBN 0442295758
• Swalin RA 1962, Thermodynamics of Solids, John Wiley & Sons, New York
• Swift EH & Schaefer WP 1962, Qualitative Elemental Analysis, WH Freeman, San Francisco
• Swink LN & Carpenter GB 1966, 'The Crystal Structure of Basic Tellurium Nitrate, Te₂O₄•HNO₃', Acta Crystallographica, vol. 21, no. 4, pp. 578–83, doi:10.1107/S0365110X66003487
• Szpunar J, Bouyssiere B & Lobinski R 2004, 'Advances in Analytical Methods for Speciation of Trace Elements in the Environment', in AV Hirner & H Emons (eds), Organic Metal and Metalloid Species in the Environment: Analysis, Distribution Processes and Toxicological Evaluation, Springer-Verlag, Berlin, pp. 17–40, ISBN 3540208291
• Taguena-Martinez J, Barrio RA & Chambouleyron I 1991, 'Study of Tin in Amorphous Germanium', in JA Blackman & J Tagüeña (eds), Disorder in Condensed Matter Physics: A Volume in Honour of Roger Elliott, Clarendon Press, Oxford, ISBN 019853938X, pp. 139–44
• Taniguchi M, Suga S, Seki M, Sakamoto H, Kanzaki H, Akahama Y, Endo S, Terada S & Narita S 1984, 'Core-Exciton Induced Resonant Photoemission in the Covalent Semiconductor Black Phosphorus', Solid State Communications, vo1. 49, no. 9, pp. 867–70
• Tao SH & Bolger PM 1997, 'Hazard Assessment of Germanium Supplements', Regulatory Toxicology and Pharmacology, vol. 25, no. 3, pp. 211–19, doi:10.1006/rtph.1997.1098
• Taylor MD 1960, First Principles of Chemistry, D. Van Nostrand, Princeton, New Jersey
• Thayer JS 1977, 'Teaching Bio-Organometal Chemistry. I. The Metalloids', Journal of Chemical Education, vol. 54, no. 10, pp. 604–6, doi:10.1021/ed054p604
• The Economist 2012, 'Phase-Change Memory: Altered States', Technology Quarterly, September 1
• The American Heritage Science Dictionary 2005, Houghton Mifflin Harcourt, Boston, ISBN 0618455043
• The Chemical News 1897, 'Notices of Books: A Manual of Chemistry, Theoretical and Practical, by WA Tilden', vol. 75, no. 1951, p. 189
• Thomas F, Bialek B & Hensel R 2013, 'Medical Use of Bismuth: The Two Sides of the Coin', Journal of Clinical Toxicology, special issue 3, article 4, doi:10.4172/2161-0495
• Thomson, T. 1830, The History of Chemistry, volumes 1–2, Henry Colburn, and Richard Bentley, London
• Tilden WA 1876, Introduction to the Study of Chemical Philosophy, D. Appleton and Co., New York
• Timm JA 1944, General Chemistry, McGraw-Hill, New York
• Togaya M 2000, 'Electrical Resistivity of Liquid Carbon at High Pressure', in MH Manghnani, W Nellis & MF.Nicol (eds), Science and Technology of High Pressure, proceedings of AIRAPT-17, Honolulu, Hawaii, 25–30 July 1999, vol. 2, Universities Press, Hyderabad, pp. 871–4, ISBN 8173713391
• Tominaga J 2006, 'Application of Ge–Sb–Te Glasses for Ultrahigh Density Optical Storage', in AV Kolobov (ed.), Photo-Induced Metastability in Amorphous Semiconductors, Wiley-VCH, pp. 327–7, ISBN 3527608664
• Träger F 2007, Springer Handbook of Lasers and Optics, Springer, New York, ISBN 9780387955797
• Traynham JG 1989, 'Carbonium Ion: Waxing and Waning of a Name', Journal of Chemical Education, vol. 63, no. 11, pp. 930–3, doi:10.1021/ed063p930
• Trivedi Y, Yung E & Katz DS 2013, 'Imaging in Fever of Unknown Origin', in BA Cunha (ed.), Fever of Unknown Origin, Informa Healthcare USA, New York, pp. 209–228, ISBN 0849336155
• Turner M 2011, 'German E. Coli Outbreak Caused by Previously Unknown Strain', Nature News, 2 Jun, doi:10.1038/news.2011.345
• Turova N 2011, Inorganic Chemistry in Tables, Springer, Heidelberg, ISBN 9783642204869
• Tuthill G 2011, 'Faculty profile: Elements of Great Teaching', The Iolani School Bulletin, Winter, viewed 29 October 2011
• Tyler PM 1948, From the Ground Up: Facts and Figures of the Mineral Industries of the United States, McGraw-Hill, New York
• Tyler Miller G 1987, Chemistry: A Basic Introduction, 4th ed., Wadsworth Publishing Company, Belmont, California, ISBN 0534069126
• Uden PC 2005, 'Speciation of Selenium,' in R Cornelis, J Caruso, H Crews & K Heumann (eds), Handbook of Elemental Speciation II: Species in the Environment, Food, Medicine and Occupational Health, John Wiley & Sons, Chichester, pp. 346–65, ISBN 0470855983
• US Air Force Medical Service 1966, The Pharmacy Technician, Department of the Air Force, Washington
• US Bureau of Naval Personnel 1965, Shipfitter 3 & 2, US Government Printing Office, Washington
• US Environmental Protection Agency 1988, Ambient Aquatic Life Water Quality Criteria for Antimony (III), draft, Office of Research and Development, Environmental Research Laboratories, Washington
• Van der Put PJ 1998, The Inorganic Chemistry of Materials: How to Make Things Out of Elements, Plenum, New York, ISBN 0306457318
• Van Setten MJ, Uijttewaal MA, de Wijs GA & Groot RA 2007, 'Thermodynamic Stability of Boron: The Role of Defects and Zero Point Motion', Journal of the American Chemical Society, vol. 129, no. 9, pp. 2458–65, doi:10.1021/ja0631246
• Vasáros L & Berei K 1985, 'General Properties of Astatine', pp. 107–28, in Kugler & Keller
• Vernon RE 2013, 'Which Elements Are Metalloids?', Journal of Chemical Education, vol. 90, no. 12, pp. 1703–1707, doi:10.1021/ed3008457
• Walters D 1982, Chemistry, Franklin Watts Science World series, Franklin Watts, London, ISBN 0531045811
• Wanga WH, Dongb C & Shek CH 2004, 'Bulk Metallic Glasses', Materials Science and Engineering Reports, vol. 44, nos 2–3, pp. 45–89, doi:10.1016/j.mser.2004.03.001
• Warren J & Geballe T 1981, 'Research Opportunities in New Energy-Related Materials', Materials Science and Engineering, vol. 50, no. 2, pp. 149–98, doi:10.1016/0025-5416(81)90177-4
• Watt GW 1958, Basic Concepts in Chemistry, McGraw-Hill, New York
• Wells AF 1984, Structural Inorganic Chemistry, 5th ed., Clarendon, Oxford, ISBN 0198553706
• Whitten KW, Davis RE, Peck LM & Stanley GG 2007, Chemistry, 8th ed., Thomson Brooks/Cole, Belmont, California, ISBN 0495014494
• Wiberg N 2001, Inorganic Chemistry, Academic Press, San Diego, ISBN 0123526515
• Wilkie CA & Morgan AB 2009, Fire Retardancy of Polymeric Materials, CRC Press, Boca Raton, Florida, ISBN 1420083996
• Witt AF & Gatos HC 1968, 'Germanium', in CA Hampel (ed.), The Encyclopedia of the Chemical Elements, Reinhold, New York, pp. 237–44
• Woodward WE 1948, Engineering Metallurgy, Constable, London
• WPI-AIM (World Premier Institute – Advanced Institute for Materials Research) 2012, 'Bulk Metallic Glasses: An Unexpected Hybrid', AIMResearch, Tohoku University, Sendai, Japan, 30 April
• Wulfsberg G 1991, Principles of Descriptive Inorganic Chemistry, Brooks/Cole, Monterey, California, ISBN 0935702660
• Wulfsberg G 2000, Inorganic Chemistry, University Science Books, Sausalito California, ISBN 1891389017
• Yacobi BG & Holt DB 1990, Cathodoluminescence Microscopy of Inorganic Solids, Plenum, New York, ISBN 0306433141
• Yasuda E, Inagaki M, Kaneko K, Endo M, Oya A & Tanabe Y 2003, Carbon Alloys: Novel Concepts to Develop Carbon Science and Technology, Elsevier Science, Oxford, pp. 3–11 et seq, ISBN 0080441637
• Young RV & Sessine S (eds) 2000, World of Chemistry, Gale Group, Farmington Hills, Michigan, ISBN 0787636509
• Young TF, Finley K, Adams WF, Besser J, Hopkins WD, Jolley D, McNaughton E, Presser TS, Shaw DP & Unrine J 2010, 'What You Need to Know About Selenium', in PM Chapman, WJ Adams, M Brooks, CJ Delos, SN Luoma, WA Maher, H Ohlendorf, TS Presser & P Shaw (eds), Ecological Assessment of Selenium in the Aquatic Environment, CRC, Boca Raton, Florida, pp. 7–45, ISBN 1439826773
• Zhang TC, Lai KCK & Surampalli AY 2008, 'Pesticides', in A Bhandari, RY Surampalli, CD Adams, P Champagne, SK Ong, RD Tyagi & TC Zhang (eds), Contaminants of Emerging Environmental Concern, American Society of Civil Engineers, Reston, Virginia, ISBN 9780784410141, pp. 343–415
• Zingaro RA 1994, 'Arsenic: Inorganic Chemistry', in RB King (ed.) 1994, Encyclopedia of Inorganic Chemistry, John Wiley & Sons, Chichester, pp. 192–218, ISBN 0471936200

Monographs

• Brady JE, Humiston GE & Heikkinen H 1980, 'Chemistry of the Representative Elements: Part II, The Metalloids and Nonmetals', in General Chemistry: Principles and Structure, 2nd ed., SI version, John Wiley & Sons, New York, pp. 537–591, ISBN 0471063150
• Chedd G 1969, Half-way Elements: The Technology of Metalloids, Doubleday, New York
• Dunstan S 1968, 'The Metalloids', in Principles of Chemistry, D. Van Nostrand Company, London, pp. 407–39
• Goldsmith RH 1982, 'Metalloids', Journal of Chemical Education, vol. 59, no. 6, pp. 526–527, doi:10.1021/ed059p526
• Hawkes SJ 2001, 'Semimetallicity', Journal of Chemical Education, vol. 78, no. 12, pp. 1686–7, doi:10.1021/ed078p1686
• Metcalfe HC, Williams JE & Castka JF 1974, 'Aluminum and the Metalloids', in Modern Chemistry, Holt, Rinehart and Winston, New York, pp. 538–57, ISBN 0030894506
• Moeller T, Bailar JC, Kleinberg J, Guss CO, Castellion ME & Metz C 1989, 'Carbon and the Semiconducting Elements', in Chemistry, with Inorganic Qualitative Analysis, 3rd ed., Harcourt Brace Jovanovich, San Diego, pp. 751–75, ISBN 0155064924
• Rieske M 1998, 'Metalloids', in Encyclopedia of Earth and Physical Sciences, Marshall Cavendish, New York, vol. 6, pp. 758–9, ISBN 0761405518 (set)
• Rochow EG 1966, The Metalloids, DC Heath and Company, Boston
• Vernon RE 2013, 'Which Elements are Metalloids?', Journal of Chemical Education, vol. 90, no. 12, pp. 1703–7, doi:10.1021/ed3008457