Talk:Chemical element

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reference to Atomism and the writings of Leucippus and Democritus[edit]

I think I reference should be included in the history section to Atomism and the writing of Leucippus and Democritus, whose ideas about atoms are, in some ways, are much closer to the modern understanding of elements, than the ideas of Plato, Aristotle etc which they inspired. How can this be done though without breaking the flow of the current text? Yugyug (talk) 16:52, 9 December 2009 (UTC)

Definition[edit]

I've always thought that a chemical element is a... er... totality of atoms with the same number of protons/same atomic number, but not a chemical substance. It seemed to me that elementery substance is the right term for a substance consisiting of atoms of the same chemical element only. Anyway, the definition is a mess: "A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons."--Adnyre (talk) 11:05, 9 January 2010 (UTC)

Consider this: chemical element
1. A species of atoms; all atoms with the same number of protons in the atomic nucleus.
2. A pure chemical substance composed of atoms with the same number of protons in the atomic nucleus. Sometimes this concept is called the elementary substance as distinct from the chemical element as defined under 1, but mostly the term chemical element is used for both concepts.
IUPAC Compendium of Chemical Terminology 2nd Edition (1997)
We should rewrite the definition.--Adnyre (talk) 11:31, 9 January 2010 (UTC)

Chemically pure and isotopically pure[edit]

OK, the above problem in the intro was apparently resolved by deleting the repetitious second sentence. But today a second conflicting definition was added to the Allotropy section, stating that a pure element is one that consists of only one stable isotope. This is also referred to a reliable source, namely the European Nuclear Society website. However it conflicts with the definition in the intro - for example, carbon is a pure element according to the first definition (since all its atoms have 6 protons) but NOT according to the second (since it has two stable isotopes, C-12 and C-13). A quick Google search suggests that both definitions have many adherents.

So what should this article say? Since there seem to be two widely accepted definitions, we should present them both and make the distinction clear. I suggest we first present the older definition (same element, same number of protons) which is described as chemically pure when the distinction is important. In the next paragraph of the intro (not in the Allotropy section) we can follow with the second definition which is often described as isotopically pure.Dirac66 (talk) 02:11, 14 August 2013 (UTC)

Archiving[edit]

Does anyone object to me setting up automatic archiving for this page using MiszaBot? Unless otherwise agreed, I would set it to archive threads that have been inactive for 30 days and keep ten threads.--Oneiros (talk) 13:57, 24 January 2010 (UTC)

Yes check.svg Done--Oneiros (talk) 00:50, 6 February 2010 (UTC)

Astronomical Californium[edit]

In Description

Cf-254 has been detected in supernova IC-4182 during 1956. ref. "Californium-254 and Supernovae" Burbidge et. al. in Phys. Rev. 103, 1145 (1956) URL:http://link.aps.org/doi/10.1103/PhysRev.103.1145 DOI:10.1103/PhysRev.103.1145

67.149.25.179 (talk) 19:10, 14 February 2010 (UTC) darianjenkins at googlemail

I am suspicious because the Cf-254 identification was done merely by the lifetime of 55 days - too weak an argument to me. Materialscientist (talk) 23:29, 14 February 2010 (UTC)

Why not astronomical Curium?[edit]

If californium is detected in supernova, presumably there should be curium which is a lighter element. The alpha decay of Californium can also produce curium. It is interesting to note that the half lives of primordial Pu-244 (8.0 * 107a) and Cm-247 (1.67 * 107a) are comparable.Anoop.m (talk) 17:59, 6 March 2011 (UTC)


Look at the date on that paper! This is 55-year old data which is now believed to have been misinterpreted. It is now thought that supernova light curves are driven by the decay of 56No and 56Co, not 254Cf. Check http://en.wikipedia.org/wiki/Supernova and references therein. — Preceding unsigned comment added by 150.203.36.23 (talk) 07:14, 8 January 2013 (UTC)

Element books[edit]

WP:ELEMENTS started creating books on each individual elements. Since there are a lot of them, any help would be very much appreciated. Headbomb {ταλκκοντριβς – WP Physics} 02:40, 28 February 2010 (UTC)

Misusing of refs[edit]

Jagged 85 (talk · contribs) is one of the main contributors to Wikipedia (over 67,000 edits; he's ranked 198 in the number of edits), and practically all of his edits have to do with Islamic science, technology and philosophy. This editor has persistently misused sources here over several years. This editor's contributions are always well provided with citations, but examination of these sources often reveals either a blatant misrepresentation of those sources or a selective interpretation, going beyond any reasonable interpretation of the authors' intent. Please see: Wikipedia:Requests for comment/Jagged 85. The damage is so extensive that it is undermining Wikipedia's credibility as a source. I searched the page history, and found 7 edits by Jagged 85 (for example, see this edits). Tobby72 (talk) 21:26, 14 June 2010 (UTC)

I took this out because it deals with "the exhaltation theory of metals" not "elements"

Building on the theory, Arab/Persian chemist and alchemist, [[Jābir ibn Hayyān]] (Geber c. 790), postulated that [[metal]]s were formed out of two elements: [[sulfur]], ‘the stone that burns’, which characterized the principle of combustibility, and [[Mercury (element)|mercury]], which contained the idealized principle of metallic properties.<ref name="r8">Strathern, Paul. (2000). Mendeleyev’s Dream – the Quest for the Elements. New York: Berkley Books.</ref> Shortly thereafter, this evolved into the Arabic concept of the three principles: sulfur giving flammability or combustion, mercury giving volatility and stability, and in the 10th century, [[Islamic medicine|Persian physician]] and alchemist [[Muhammad ibn Zakarīya Rāzi]] (Rhazes) hints at [[Salt (chemistry)|salt]] giving solidity. In 1524, Swiss chemist [[Paracelsus]] adopted Aristotle’s four element theory, but reasoned that they appeared in bodies as three principles. Paracelsus saw these principles as fundamental, and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke represented the volatility (the mercury principle), the heat-giving flames represented flammability (sulfur), and the remnant ash represented solidity (salt).<ref name="r8"/> In 1669, German physician and chemist [[Johann Becher]] published his Physica Subterranea. In modification on the ideas of Paracelsus, he argued that the constituents of bodies are air, water, and three types of earth: ''terra fluida'', the mercurial element, which contributes fluidity and volatility; ''terra lapida'', the solidifying element, which produces fusibility or the binding quality; and ''terra pinguis'', the fatty element, which gives material substance its oily and combustible qualities.<ref name="r9">Partington, J.R. (1937). A Short History of Chemistry. New York: Dover Publications, Inc.</ref> These three earths correspond with Geber’s three principles. A piece of wood, for example, according to Becher, is composed of ash and terra pinguis; when the wood is burnt, the terra pinguis is released, leaving the ash. In other words, in combustion the fatty earth burns away.

J8079s (talk) 19:54, 31 July 2010 (UTC)

Dubious[edit]

In the section on history it states that the term "element" was originally used to refer to states of matter. It goes on to list the relevant elements and their associated states of matter: solid/earth, liquid/water, gas/air, and plasma/fire. I don't believe that this statement is accurate. The original Classical elements were devised in ancient times (roughly Hellenistic era), but plasma wasn't discovered until the 19th century. The connection is tenuous. (And tt sounds like new-age hokum to me.) I think the first part of this section should be changed or removed completely. Danshil (talk) 15:58, 5 July 2010 (UTC)

I agree. It's quite plausible that the names originated from natural observations of phases of matter (clearly not plasma, except the sun and stars) however, the philosophical theories weren't equivalent to phases of matter. Once aether was no longer needed for celestial mechanics, the name was reused, sometimes in connection with odic force but most recently as the luminiferous aether. But that's TMI for this article.
I took out the global statement saying "they're all the same" because they're only similar due to everyone living on the same planet observing the same phenomena. There actually were theoretical differences. The classical elements article is able to compare and contrast the various theories but, again, that's TMI here and Greek philosophy is the proper basis for comparison for history of science. Thanks—Machine Elf 1735 (talk) 18:13, 5 July 2010 (UTC)
Concur just to put down a note: the peripatetics with Plato, Aristotle and a couple of other guys imagined that every element was composed from thingies that looked like the platonic solids, of exactly five kinds. They imagined that the triangles were kind of abstract "atoms", rejecting the more modern-looking atomism of Democritus. The elements "water", "fire", "earth", "air" and "ether" was nothing like "states of matter", they were more like the essence of their respective practical manifestation if such a weird thing can be imagined these days. Rursus dixit. (mbork3!) 12:04, 21 March 2011 (UTC)
Er, peripatetics (as opposed to "academics") were connected with Aristotle's school at the Lyceum (as opposed to Plato's Academy).
Aristotle rejected Plato's quasi-atom interpretation, which was no-doubt inspired by the Pythagoreans. Aristotle thought triangles were abstractions, and while they composed abstract "solids", they could not be said to compose real substance. Aristotle was ever-so-much more the materialist than Plato, although the atomists, in general, were strictly materialist (and Plato isn't counted among them, except to mention his solids in connection with the elements).
Aristotle gave an entirely different account of the transformation between the elements, (the change between "states of matter", coupled with cosmogonical considerations and a general explanation of what it means for something to change). Aristotle's hylomorphic reinterpretation of Plato's theory of forms implied the elements can't exist in pure form because they're intended to account for prime matter (and matter cannot exist without form). Form, for Aristotle, is an abstract description of something, entirely "before" or entirely "after" whatever change is being discussed.
The elemental forms were thus abstractions of "a potential to do work", that of heating or desiccating, which are always a "mixture" as found in nature (in various ratios). So abstractly, fire is what's hot (but dry), air is what's moist (but hot), water is what's cold (but moist), and earth is what's dry (but cold).
Aristotle was concerned to eliminate the possibility of an indeterminate form (some intermediate state) during an elemental transformation. His solution was similar to Gray code in modern communication and computing, multiple "contrarieties" don't undergo change simultaneously: for example, fire can't change directly to earth, the change must be analyzed as two stages: either fire→air→earth or fire→water→earth.
Anyway, selective accounts of Democritus (notably Bertrand Russell's A History of Western Philosophy) are tenuously "modern-looking", but a string of lucky guesses are impressive in a way even Aristotle would have characterized as non-scientific.—Machine Elf 1735 08:22, 22 March 2011 (UTC)

Elements found in nature[edit]

There are several different numbers of elements occuring naturally in nature that are thrown around on this page. Could we reach a consensus on the correct amount? --69.81.137.79 (talk) 03:29, 22 August 2010 (UTC)tytyytytytytyty

Did you read it carefully? Give an example of a discrepancy (making sure you're not giving example of what are different figures for what are actually two different things) SBHarris 17:26, 28 February 2011 (UTC)
He might have been right in 22 August 2010: there were mentionings of the speculative discoveries elements 122 and 126, at that time that a small minority of physicists believed could be factual. Those alleged discoveries were later retracted so now it is almost universally 118 elements (or less), where 117 is the latest plausible discovery. In other words: we've gotten the numbers right now. Rursus dixit. (mbork3!) 12:16, 21 March 2011 (UTC)
Nothing like 118 elements are found in nature. 94 elements are found in nature-- the rest are made artificially, with increasingly small half-lives. Saying element 118 is found in nature is like saying automobiles are found in nature. That isn't what we mean by the phrase in English.SBHarris 16:35, 21 March 2011 (UTC)

These numbers seem to conflict. If they don't, then the writing is not clear enough for a lay reader. "As of 2010, there are 118 known elements .... Of these 118 elements, 98 occur naturally on Earth." "Of the 94 naturally occurring elements, those with atomic numbers 1 through 40 are all considered to be stable isotopes."

And these as well: "As of 2010, there are 118 known elements ... The first 98 elements have been detected directly on Earth as primordial nuclides present from the formation of the solar system, or as naturally-occurring fission or transmutation products of uranium and thorium.... The remaining 24 heavier elements, not found today either on Earth or in astronomical spectra, have been derived artificially." — Preceding unsigned comment added by 74.128.70.142 (talk) 04:03, 6 March 2012 (UTC)

Last week this edit removed 6 elements from the list and changed the total to 92 in part of the article, although the Description section still says 98. I suspect 98 is correct but I am not certain. Could someone please check this out and restore consistency and correctness? Dirac66 (talk) 00:11, 28 June 2014 (UTC)

Emsley in Nature's Building Blocks says that 5 isotopes of Cf are detectable in U deposits. See http://books.google.com/books?id=4BAg769RfKoC&pg=PA109&lpg=PA109&dq=emsley+nature%27s+building+blocks+californium&source=bl&ots=k11iK0RLxG&sig=_R1t7BeaJvrHUgwth33vnLe_rcc&hl=en&sa=X&ei=oBeuU8SJC47soATSwIG4Cw&ved=0CC8Q6AEwAg#v=onepage&q=emsley%20nature%27s%20building%20blocks%20californium&f=false This reference is also used in the californium Wiki article. But 98 is the highest we see today on Earth, as 99 and 100 require the r-process with 15 and 17 rapid neutron captures, so you only see them in operating reactors, H-bomb detonations, etc. They may have been made in the natural Oklo reactor, but are all gone now (not detectable). So 98 is correct. I'll just lift the Emsley ref from the Cf article, and put it back the way it was. BTW, "primordial" means since the beginning of the solar system, not since the Big Bang. Be, B, and Li are cosmogenic AND primordial. SBHarris 01:36, 28 June 2014 (UTC)

Thanks for clarifying and for fixing the intro section. I have also fixed the Occurrence and Origin section to be consistent, by reverting the edit I mentioned from last week. Dirac66 (talk) 22:29, 28 June 2014 (UTC)

Table summarizing origin of elements?[edit]

Would it be useful to augment the information in element table within this article with a new column showing the origin of the element (big-bang, stellar, supernova, etc)? Perhaps augment the primordial/transitory/synthesis column? Or an additional column? See Nucleosynthesis, Big Bang nucleosynthesis, Stellar nucleosynthesis, and Supernova nucleosynthesis. This article already has an "Origins" section which discusses these origins in general terms, but I was looking for a tabular summary, per-element. --Noleander (talk) 20:15, 7 July 2011 (UTC)

After studying the "List of the 118 known chemical elements" table, I propose to implement the above suggestion by changing the entries in the "Occurrence" column by replacing "primordial" entries with three more specific choices: Big Bang nucleosynthesis, Stellar nucleosynthesis, or Supernova nucleosynthesis. If unknown, I could just leave it as "primordial" or perhaps "nucleosynthesis". The "Transitory" and "Synthesized" entries would not be changed. Comments? --Noleander (talk) 03:39, 8 July 2011 (UTC)
I find this table and accompanying text unsatisfactory on several levels. Firstly it contradicts the introduction on the origin of lithium, beryllium and boron. Secondly it (and the intro) imply that all hydrogen and helium is of primordial origin, and do not allow for the Stellar nucleosynthesis of helium which is still happening in most stars, including our sun. Furthermore, lithium to boron are referred to as primordial with a spallation origin. This is logically nonsense, since spallation requires a pre-existing heavier element such as carbon, which according to the article derives from stellar nucleosynthesis, i.e. NOT primordial. Much more clarity is required here. The most serious fault is the implication that elements heavier than hydrogen are not still being produced currently. Plantsurfer (talk) 10:52, 18 May 2013 (UTC)
The column heading should be Origin (how it was formed) rather than Occurrence (how much is found now and where). Noleander's breakdown of primordial into 3 categories is a good idea, but we should also add cosmic ray spallation. Also the data for each element can include more than one origin in order of estimated importance. For He, Big Bang first, then stellar nucleosynthesis. For Li, Big Bang then cosmic ray spallation. And so on. Dirac66 (talk) 21:58, 18 May 2013 (UTC)

Error in atomic masses?[edit]

this is error right? "the atomic weight of chlorine-35 to five significant digits is 34.969 u" "relative atomic mass of chlorine is 35.453 u" if yes please fix it, somebody. — Preceding unsigned comment added by 178.219.186.200 (talk) 20:05, 1 May 2014 (UTC)

The two values are both correct but they refer to different things. Chlorine has two stable isotopes - chlorine-35 and chlorine-37. The value 34.969 is the mass of chlorine-35 only. The value 35.453 is the weighted average of both isotopes, and is closer to 35 than to 37 because there is more Cl-35 than Cl-37. This is all explained in the section Atomic mass and atomic weight. Dirac66 (talk) 20:46, 1 May 2014 (UTC)
I looked here http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl the Relative Atomic Mass and Standard Atomic Weight of chlorine-35 and it was 34.968 852 68(4) and 35.453(2), respectively, unlike in quotations I pointed above. I mean here "relative atomic mass of chlorine is 35.453 u" must be 34.969 and here "the atomic weight of chlorine-35 to five significant digits is 34.969 u" must be 35.453. Lufnuf (talk) 22:33, 1 May 2014 (UTC)
and instead of "atomic weight of chlorine-35" must be chlorine without number and chlorine-35 here "relative atomic mass of chlorine is 35.453 u"

I think that part of article (Atomic mass and atomic weight) must be revised. Lufnuf (talk) 23:56, 1 May 2014 (UTC)

The layout of the physics.nist.gov link is a little confusing. The values in the columns Relative Atomic Mass and Isotopic Composition refer to individual isotopes (such as Cl-35), but the values in the column Standard Atomic Weight refer to an average for the element (such as Cl). That is why this column has only one value for each element. If you click on the words Standard Atomic Weight at the top of the column, you will find the NIST explanation, starting with the words: The relative atomic mass of an element is derived by averaging the relative atomic masses of the isotopes of that element. So the values are both correct.
I do however now see some changes which may make this section clearer. The title Atomic mass and atomic weight wrongly suggests that the difference between mass and weight is important here. I will change it to Isotopic mass and atomic mass in order to emphasize the important difference between the two values such as Cl-35 and Cl. All the values are now considered as masses, so we only need to mention once that weight was used historically. And finally I will place this section after the Isotopes section, since we should define isotopes before talking about them. Dirac66 (talk) 02:38, 2 May 2014 (UTC)