Glossary of chemistry terms

Chemistry
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This page is a glossary of chemistry terms. Chemistry has an extensive vocabulary and a significant amount of jargon. This is a list of chemical terms, including laboratory tools, glassware, and equipment. Chemistry itself is a physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.

Note: All periodic table references refer to the IUPAC Style of the Periodic Table

A

An atom, with protons, neutrons, and electrons labelled.

• absolute zero - a theoretical condition concerning a system at zero Kelvin where a system does not emit or absorb energy (all atoms are at rest)
• accuracy - how close a value is to the actual or true value; also see precision
• acid - a compound that, when dissolved in water, gives a pH of less than 7.0 or a compound that donates a hydrogen ion
• acid anhydride - a compound with two acyl groups bound to a single oxygen atom
• acid dissociation constant - an equilibrium constant for the dissociation of a weak acid
• actinides - the fifteen chemical elements that are between actinium (89) and lawrencium (103)
• activated complex - a structure that forms because of a collision between molecules while new bonds are formed
• activation energy
• activity series
• actual yield
• addition reaction - within organic chemistry, when two or more molecules combine to make a larger one
• aeration - the mixing of air into a liquid or solid
• alkali metals - the metals of Group 1 on the periodic table
• alkaline earth metals - the metals of Group 2 on the periodic table
• allomer - a substance that has different composition than another, but has the same crystalline structure
• allotropy - elements that can have different structures (and therefore different forms), such as Carbon (diamonds, graphite, and fullerene)
• anion - negatively charge ions
• anode
• aromaticity - chemical property of conjugated rings that results in unusual stability. See also benzene.
• atom - a chemical element in its smallest form, and is made up of neutrons and protons within the nucleus and electrons circling the nucleus
• atomic mass unit
• atomic number - the number representing an element which corresponds with the number of protons within the nucleus
• atomic orbital - the region where the electron of the atom may be found
• average atomic mass
• Avogadro's law
• Avogadro's number

B

• barometer -
• base - a substance that accepts a proton and has a high pH; a common example is sodium hydroxide (NaOH)
• biochemistry - the chemistry of organisms
• boiling - the phase transition of liquid vaporizing
• boiling point -
• boiling-point elevation -
• bond - the attraction and repulsion between atoms and molecules that is a cornerstone of chemistry
• Boyle's law -
• Brønsted-Lowrey acid -
• Brønsted–Lowry acid–base reaction -
• Brønsted-Lowrey base -
• buffered solution -
• burette (also buret) - glassware used to dispense specific amounts of liquid when precision is necessary (e.g. titration and resource dependent reactions)

C

An example of combustion

• catalyst - a chemical compound used to change the rate (either to speed up or slow down) of a reaction, but is regenerated at the end of the reaction.
• cation - positively charged ion
• centrifuge - equipment used to separate substances based on density by rotating the tubes around a centred axis
• cell potential - the force in a galvanic cell that pulls electron through reducing agent to oxidizing agent
• chemical Law - certain rules that pertain to the laws of nature and chemistry - examples
• chemical reaction - the change of one or more substances into another or multiple substances
• colloid - mixture of evenly dispersed substances, such as many milks
• combustion - an exothermic reaction between an oxidant and fuel with heat and often light
• compound - a substance that is made up of two or more chemically bonded elements
• condensation - the phase change from gas to liquid
• conductor - material that allows electric flow more freely
• covalent bond - chemical bond that involves sharing electrons
• crystal - a solid that is packed with ions, molecules or atoms in an orderly fashion
• cuvette - glassware used in spectroscopic experiments. It is usually made of plastic, glass or quartz and should be as clean and clear as possible

D

• deionization - the removal of ions, and in water's case mineral ions such as sodium, iron and calcium
• deliquescence - substances that absorb water from the atmosphere to form liquid solutions
• deposition - settling of particles within a solution or mixture
• dipole - electric or magnetic separation of charge
• dipole moment - the polarity of a polar covalent bond
• dissolution or solvation - the spread of ions in a solvent
• double bond - sharing of two pairs of electrons

E

Microcentrifuge or Eppendorf tube with Coomassie Blue solution

• earth metal - see alkaline earth metal
• electrolyte - a solution that conducts a certain amount of current and can be split categorically as weak and strong electrlytes
• electrochemical cell - using a chemical reaction's current, electromotive force is made
• electromagnetic radiation - a type of wave that can go through vacuums as well as material and classified as a self-propagating wave
• electromagnetism - fields that have electric charge and electric properties that change the way that particles move and interact
• electromotive force - a device that gains energy as electric charges pass through it
• electron - a subatomic particle with a net charge that is negative
• electron shells - an orbital around the atom's nucleus that has a fixed number electrons (usually two or eight)
• electric charge - a measured property (coulombs) that determine electromagnetic interaction
• element - an atom that is defined by its atomic number
• energy - A system's ability to do work
• enthalpy - measure of the total energy of a thermodynamic system (usually symbolized as H)
• entropy - the amount of energy not available for work in a closed thermodynamic system (usually symbolized as S)
• enzyme - a protein that speeds up (catalyses) a reaction
• eppendorf tube - generalized and trademarked term used for a type of tube; see microcentrifuge

F

• freezing - phase transition from liquid to solid
• Faraday constant - a unit of electrical charge widely used in electrochemistry and equal to ~ 96,500 coulombs.

It represents 1 mol of electrons, or the Avogadro number of electrons: 6.022 × 10²³ electrons. F = 96 485.339 9(24) C/mol

• Faraday's law of electrolysis - a two part law that Michael Faraday published about electrolysis
  • the mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode
  • the mass of an elemental material altered at an electrode is directly proportional to the element's equivalent weight.
• frequency - number of cycles per unit of time. Unit: 1 hertz = 1 cycle per 1 second

G

• galvanic cell - battery made up of electrochemical with two different metals connected by salt bridge
• gas - particles that fill their container though have no definite shape or volume
• geochemistry - the chemistry of and chemical composition of the Earth
• Gibbs energy - value that indicates the spontaneity of a reaction (usually symbolized as G)

H

• halogens - Group 17 on the Periodic Table and are all non-metals

J

• jodium – Latin name of the halogen element iodine

I

• indicator - a special compound added to solution that changes color depending on the acidity of the solution; different indicators have different colors and effective pH ranges
• inorganic compound - compounds that do not contain carbon, though there are exceptions (see main article)
• inorganic chemistry - a part of chemistry concerned with inorganic compounds
• International Union of Pure and Applied Chemistry (IUPAC) -
• insulator - material that resists the flow of electric current
• ion - a molecule that has gained or lost one or more electrons
• ionic bond - electrostatic attraction between oppositely charged ions
• ionization -The breaking up of a compound into separate ions.

K

• Kinetics - A sub-field of chemistry specializing in reaction rates
• Kinetic energy - The energy of an object due to its motion.

L

• lanthanides - Elements 57 through 71
• lattice - Unique arrangement of atoms or molecules in a crystalline liquid or solid.
• Laws of thermodynamics
• liquid - A state of matter which takes the shape of its container
• light - Portion of the electromagnetic spectrum which is visible to the naked eye. Also called "visible light."
• London dispersion forces - A weak intermolecular force

M

This is a molecule, which is one of the key components within chemistry

• Metal - Chemical element that is a good conductor of both electricity and heat and forms cations and ionic bonds with non-metals.
• melting - The phase change from a solid to a liquid
• metalloid - A substance possessing both the properties of metals and non-metals
• methylene blue - a heterocyclic aromatic chemical compound with the molecular formula C₁₆H₁₈N₃SCl
• microcentrifuge - a small plastic container that is used to store small amounts of liquid
• mole - abbreviated mol - a measurement of an amount of substance; a single mole contains approximately 6.022×10²³ units or entities
  • a mole of water contains 6.022×10²³ H₂O molecules
• molecule - a chemically bonded number of atoms that are electrically neutral
• molecular orbital - region where an electron can be found in a molecule (as opposed to an atom)

N

• neutron - a neutral unit or subatomic particle that has no net charge
• neutrino - a particle that can travel at speeds close to the speed of light and are created as a result of radioactive decay
• nucleus - the centre of an atom made up of neutrons and protons, with a net positive charge
• noble gases - group 18 elements, those whose outer electron shell is filled
• non-metal - an element which is not metallic
• nuclear - of or pertaining to the atomic nucleus
• nuclear magnetic resonance spectroscopy - technique that exploits the magnetic properties of certain nuclei, useful for identifying unknown compounds
• number density – a measure of concentration of countable objects (atoms, molecules, etc.) in space; number per volume

O

• orbital - may refer to either an atomic orbital or a molecular orbital
• organic compound - compounds that contain carbon
• organic chemistry - a part of chemistry concerned with organic compounds

P

• pH - the measure of acidity (or basicity) of a solution
• plasma - state of matter similar to gas in which a certain portion of the particles are ionized
• poor metal - Metallic elements in the p-block, characterized by lower melting and boiling points than other metals
• potential energy - energy stored in a body or in a system due to its position in a force field or due to its configuration
• precipitate - formation of a solid in a solution or inside another solid during a chemical reaction or by diffusion in a solid
• precision - How close the results of multiple experimental trials are. See also accuracy.
• photon - a carrier of electromagnetic radiation of all wavelength (such as gamma rays and radio waves)
• proton - a positive unit or subatomic particle that has a positive charge
• protonation - the addition of a proton (H⁺) to an atom, molecule, or ion

Q

• Quantum mechanics - the study of how atoms, molecules, subatomic particles, etc. behave and are structured
• quarks - elementary particle and a fundamental constituent of matter

R

• radiation - energy in the form of waves or subatomic particles when there is a change from high energy to low energy states
• radioactive decay - the process of an unstable atomic nucleus losing energy by emitting radiation

S

• s-block elements - Group 1 and 2 elements (alkali and alkaline metals), which includes Hydrogen and Helium
• salts - ionic compounds composed of anions and cations
• salt bridge - devices used to connection reduction with oxidation half-cells in an electrochemical cell
• saline solution - general term for NaCl in water
• Schrödinger equation - quantum state equation which represents the behaviour of an election around an atom
• semiconductor - an electrically conductive solid that is between a conductor and an insulator
• single bond - sharing of one pair of electrons
• sol - a suspension of solid particles in liquid. Artificial examples include sol-gels.
• solid - one of the states of matter, where the molecules are packed close together, there is a resistance of movement/deformation and volume change; see Young's modulus
• solute - the part of the solution that is mixed into the solvent (NaCl in saline water)
• solution - homogeneous mixture made up of multiple substances. It is made up of solutes and solvents.
• solvent - the part of the solution that dissolves the solute (H₂O in saline water)
• spectroscopy - study of radiation and matter, such as X-ray absorption and emission spectroscopy
• speed of light - the speed of anything that has zero rest mass (Energy_rest = mc² where m is the mass and c is the speed of light)
• Standard conditions for temperature and pressure or SATP - a standardisation used in order compare experimental results (25 °C and 100.000 kPa)
• state of matter - matter having a homogeneous, macroscopic phase; gas, plasma, liquid, and solid are the most well known (in increasing concentration)
• sublimation - a phase transition from solid to gas
• subatomic particles - particles that are smaller than an atom; examples are protons, neutrons and electrons
• substance - material with definite chemical composition

T

Phase diagram showing the triple and critical points of a substance

• talc - a mineral representing the one on the Mohs Scale and composed of hydrated magnesium silicate with the chemical formula H₂Mg₃(SiO₃)₄ or Mg₃Si₄O₁₀(OH)₂
• temperature - the average energy of microscopic motions of particles
• theoretical yield - see yield
• theory - a model describing the nature of a phenomenon
• thermal conductivity - a property of a material to conduct heat (often noted as k)
• thermochemistry - the study of absorption/release of heat within a chemical reaction
• thermodynamics - the study of the effects of changing temperature, volume or pressure (or work, heat, and energy) on a macroscopic scale
• thermodynamic stability - when a system is in its lowest energy state with its environment (equilibrium)
• thermometer - device that measures the average energy of a system
• titration - the process of titrating one solution with another, also called volumetric analysis
• torr - a unit to measure pressure (1 Torr is equivalent to 133.322 Pa or 1.3158×10⁻³ atm)
• transition metal - elements that have incomplete d sub-shells, but also may be referred to as the d-block elements
• transuranic element - element with atomic number greater than 92; none of the transuranic elements are stable
• triple bond - the sharing of three pairs of electrons within a covalent bond (example N₂)
• triple point - the place where temperature and pressure of three phases are the same (Water has a special phase diagram)
• Tyndall effect - the effect of light scattering by colloidal (mixture where one substance is dispersed evenly through another) or suspended particles

U

• UN number - a four digit code used to note hazardous and flammable substances
• uncertainty - a characteristic that any measurement that involves estimation of any amount cannot be exactly reproducible
• Uncertainty principle - knowing the location of a particle makes the momentum uncertain, while knowing the momentum of a particle makes the location uncertain
• unit cell - the smallest repeating unit of a lattice
• unit factor - statements used in converting between units
• universal or ideal gas constant - proportionality constant in the ideal gas law (0.08206 L·atm/(K·mol))

V

• valence electron - the outermost electrons of an atom, which are located in electron shells
• Valence bond theory - a theory explaining the chemical bonding within molecules by discussing valencies, the number of chemical bonds formed by an atom
• van der Waals force - one of the forces (attraction/repulsion) between molecules
• van 't Hoff factor - ratio of moles of particles in solution to moles of solute dissolved
• vapor - when a substance is below the critical temperature while in the gas phase
• vapour pressure - pressure of vapour over a liquid at equilibrium
• vaporization - phase change from liquid to gas
• viscosity - the resistance of a liquid to flow (oil)
• volt - one joule of work per coulomb - the unit of electrical potential transferred
• voltmeter - instrument that measures the cell potential
• volumetric analysis - see titration

W

• water - H₂O - a chemical substance, a major part of cells and Earth, and covalently bonded
• wave function - a function describing the electron's position in a three dimensional space
• work - the amount of force over distance and is in terms of joules (energy)

X

• X-ray - form of ionizing, electromagnetic radiation, between gamma and UV rays
• X-ray diffraction - a method for establishing structures of crystalline solids using singe wavelength X-rays and looking at diffraction pattern
• X-ray photoelectron spectroscopy - a spectroscopic technique to measure composition of a material

Y

• yield - the amount of product produced during a chemical reaction

Z

• zone melting - a way to remove impurities from an element by melting it and slowly travel down an ingot (cast)

External links

• IUPAC Compendium of Chemical Terminology