Talk:Chemical element

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Note that Bismuth, Atomic Number 83, has stable isotopes. The statement in the article that all elements with atomic numbers greater than 82 (lead) is off by one.
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[edit] why allotropes and isotope effect ruin the archaic definition

Allotropes -- it becomes very difficult to define which one truly represents "elemental" X. For example, which lattice structure best exemplifies "elemental nickel" -- they all have subtly different chemical properties. Or, better yet, should metallic gold or a gold nanoparticle (of which size?) should be "elemental gold"? even carbon, mundane and exquisitely important, has an infinite array of allotropes -- graphite, diamond, buckyballs of various radii, and nanotubes with varying dimensions, geometries, and even chiralities!

Isotope effect -- So even if we choose a "canonical" allotrope which represents element X, an 15O2 molecule has different properties than a 16O2 molecule. The isotope effect is glaring when dealing with hydrogen. So it still becomes possible to use chemical transformations (and a centrifuge -- is using "physics" cheating?) to break up an "element" in the old sense, and reassemble it into a set of compounds with different chemical properties.

Now if we choose a canonical allotrope and a canonical isotope, our definition of element becomes useless, since, a D2 molecule is a different element than an H2 molecule, and we lose any contextual meaning. The nice thing about the modern definition is that by not being a "clinical definition", it enables a synthesis of the commonalities observed between isotopes, leaves wiggle rome for differences amongst the same, and highlights gross differences between different elements. This is the hallmark of good definition.

Unless something new is discovered that confounds this definition, chemists will continue to use it. {{subst:unsigned2|08:05, 26 July 2005|67.124.223.202}

I would say that the description of each element should be that of the allotrope that is of the lowest energy at the defined standard temperature and pressure. Therefore, whichever allotrope of the atom is the lowest in energy at STP would be the definition of that element. This is why diamond would not be the representative of carbon since diamond will, over a HUGE amount of time, revert back to graphite. Yes, it is difficult to determine what the most stable/lowest energy allotrope is of an element that contains a great number of them, but it is possible. (Jdurg 23:28, 17 December 2006 (UTC))

[edit] Great photo gallery

User:RTC/element photos is a great comparison table of all the elements.--Menchi 20:44, 2 Apr 2005 (UTC)

[edit] List?

Shouldn't there be some kind of list of all the elements, so that people could find what they wanted? Technically, the whole point of this page should be to:

  1. Tell the people about what a chemical element is
  2. Introduce the periodic table as a way to organise the elements
  3. Tell what the elements are

So... Just a suggestion... you know... {{subst:unsigned2|22:34, 8 September 2005|64.16.177.145}

  • Well, what you're describing is pretty much the Periodic Table, just expanded. Go start it and lets see what you can come up with.

CherryT 03:53, 10 October 2006 (UTC)

[edit] AMU Calculation

Hello all. I wrote a brief that explains how exactly the atomic masses for elements are calculated under the section that does breifly mention the subject of mass. I'm not quite certain how and where to leave the citation for it, any input is appreciated. I am not sure if the position within the article for my breif is appropriate, again input is appreciated. This is my first major post to Wikipedia and also my first post as a user with an account. I'm looking forward to contributing to Wikipedia.

Hi Morgana The Argent, think you’re doing a great job. Regarding your questions:
  • You could also consider to put your calculation example at Atomic mass or Atomic mass unit, and leave a shorter less detailed description in this article. However, there’s no hard rule that says so.
  • The position in the article itself seems okay to me.
Congrats on your first major post. Van helsing 14:52, 7 June 2006 (UTC)
PS. You already discovered the tilde (~~~~) thingy to sign your talk page posts?

[edit] Nonelement symbols

I move this part here now .. did not belong in Chemical Compound for sure .. might need a discussion where they d belong

Nonelements, especially in organic and organometallic chemistry, often acquire symbols which are inspired by the elemental symbols. A few examples:

Suggestion: seperate article? --Dirk Beetstra T C 06:28, 4 August 2006 (UTC)

[edit] The Origin of the Elements

I've read somewhere that current science explains the origin of the elements by stating that no elements existed (except helium and hydrogen) after bigbang, but later others formed because of the cooling and heating. Is this right? Can someone add this kind of information on the page?--Quinlan Vos 15:42, 8 October 2006 (UTC)

  • ==I seem to remember this being the teaching recently at the Open University - something to do with the nuclei conjoining to make bigger atoms that then remain stable, i may be imagining this but isn't it the processes of fusion like in our sun ??

--Sumo su 21:10, 15 December 2006 (UTC)

[edit] Naturally Occuring Substances?

I just want to verify, because on the PToE page it says that there are 90 naturally occuring elements and in a textbook I have (though it may be dated). (UPDATE) I'm replacing it: Tech. and the other 2 supposed elements are manmade. CherryT 03:56, 10 October 2006 (UTC)

  • I'm just gonna leave it at 91, if tech. has truely been discovered in nature. Where are we derving the other two elements from?

CherryT 04:03, 10 October 2006 (UTC)

Wellll...it depends on what you mean by 'naturally occuring'. Of the first 92 elements (up to uranium) there exist stable isotopes of 90. (Technetium and promethium have no stable isotopes.) On the other hand, trace amounts of a number of unstable isotopes are generated through radioactive decay. For example, promethium, technetium, neptunium, and plutonium are continuously created through the decay of naturally occurring uranium ores; all four elements have been detected there. Supernova explosions generate a wealth of even heavier (but very short-lived) radioisotopes through Supernova nucleosynthesis. TenOfAllTrades(talk) 04:15, 10 October 2006 (UTC)

Let's stop the 'traditional but incorrect' view and put it at '94 naturally occurring elements on Earth.' By definition, that would exclude those found in stars, but include the six found only naturally through radioactive decay (technetium, prometium, astatine, francium, neptunium, and plutonium). Much of the 'synthetic' or artificial label idea was inappopriately applied to technetium, plutonium, etc because they were created artificially before being discovered naturally...although with the 1925 natural discovery of technetium a possibility, that may also need revision.→ R Young {yakłtalk} 09:22, 20 October 2006 (UTC)

From the article 'transuranium element':

Of the elements with atomic numbers 1 to 92, all but four (43-technetium, 61-promethium, 85-astatine, and 87-francium) occur in easily detectable quantities on earth, having stable, or very long half life isotopes, or are created as common products of the decay of uranium.

Note that as early as the 1960's, it was known that Neptunium and Plutonium could be found in nature (see McWhirter's Encyclopedia of Facts).→ R Young {yakłtalk} 09:51, 20 October 2006 (UTC)

[edit] Comment moved from top of page

The first para says there are 118 elements; the third says there are 116 and goes on to say they are divided into 94 plus 23 which makes 117. Can we have a definitive number?

- Pepper 150.203.227.130 11:14, 17 October 2006 (UTC)

Element 117 hasn't been discovered yet, while 118 was just discovered. Thus, there should be 117 elements (1-116 and 118) so far discovered, of which 94 (hydrogen to plutonium) occur on Earth in at least trace quantities (astatine being the rarest, about 1 oz existing naturally on the planet).→ R Young {yakłtalk} 09:07, 20 October 2006 (UTC)

[edit] Heavy vs. Dense

Correct me if I'm wrong, but isn't Element 118 the densest, not the heaviest element? I mean, you can have several atoms of oxygen that would be heavier than Element 118.

Yes, dense would be correct, but heaviest is also correct as three atoms of Element 118 would weigh more than (and have more mass than, as implied by the density) three oxygen atoms. Matwilko 00:43, 29 October 2006 (UTC)

Densest would only be accurate if it had the same volume as the other elements but still weighed more. If you have the same volume of Osmium as you do Ununoctium, Osmium would weigh more as it is much more dense than Ununoctium. So the term "heaviest" is more accurate since if you have the same number of atoms of Os as you do Uuo, Uuo would weigh more as it's per atom mass is greater than that of any other element. (Jdurg 00:08, 3 December 2006 (UTC))

"Density" is not calculated per atom, because it's hard to tell the volume of atoms. Density of elements requires having enough of the solid element to measure the value (atoms pack in crystals differently, so densities aren't even consistant for the SAME element at a given temp and pressure-- it all depends on structure). Density is a BULK value only, and requires having some bulk material. All this is why we speak of mass of elements (atomic weight), which is easy to measure and means the average mass of one atom. By "heavy" when we speak of an element, we mean per-atom-mass, not density. And by the way, due to the odd effects of crystal structure and individual atomic electron packing, iridium (number 77) and osmium are still the densest bulk elements of all those solid elements that exist in enough quantity that we can measure density for them. They run 22.6 or so g/mL, despite the fact that we can easily measure densities for atomically heavy U and Pu and Np, and they come out less (about 20 g/mL), even though they are all considerably heavier, per atom, than Os or Ir. Whether the superheavies win the prize for bulk density isn't known. Maybe, maybe not. My guess is they wouldn't, even if we could get enough together to measure it.SBHarris 22:12, 15 December 2006 (UTC)

[edit] Definition?

Could someone clarify this for me: The definition says "A chemical element, often called simply an element, is a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes. All matter consists of these elements and as of 2006, 117 unique elements have been discovered or artificially created. The smallest particle of such an element is an atom, which consists of electrons centered about a nucleus of protons and neutrons". What is a "substance" here? Oxygen may exist as O2 or O3, are these substances? If they are, the can be transformed into each other by a chemicl process. If not, why the distinction between "substance" and "atom"? --Manscher 14:15, 25 October 2006 (UTC)

Should be a link to chemical substance. O2 is not the element, O is the element (although the terms are used inconsistently, even by chemists), that O does not want to be alone results indeed that oxygen is always found as chemical substances. Hope this clarifies a bit (I don't know if these examples (to mind spring: H, O, N, F, Br, I, Cl, S, P) are sufficiently covered in wikipedia). --Dirk Beetstra T C 14:25, 25 October 2006 (UTC)
Thanks, your answer fits very well with my own conception of "element". --Manscher 15:05, 25 October 2006 (UTC)


[edit] These are the ten most common elements in the Universe as measured in parts per million

"Most common elements in the Universe. These are the ten most common elements in the Universe as measured in parts per million:"

  • by mass or by number of particles? --GangofOne 00:55, 6 November 2006 (UTC)
  • The abundances here are all by mass. They could as well be in mole-fraction (number of particles), but aren't. For example, the universe is about 74% H and 24% He by mass, but divide the He number by about 4 to get mole fraction. I've modified the chem abundance article to discuss this. SBHarris 22:04, 15 December 2006 (UTC)

[edit] Wrong colour in key to illustration of periodic table

The colour used for the transition metal positions in the table itself is a kind of salmon-pink, but the colour shown in the key for the transition metals seems to be the same pinkish-red that is used for the alkali metals. Kay Dekker 22:13, 20 November 2006 (UTC)

[edit] now 118 elements found - update required

117 has now been discovered

Within less than a millisecond after its creation, the element 118 nucleus decays by emitting an alpha particle, leaving behind an isotope of element 117 with mass number 289, containing 117 protons and 173 neutrons. This daughter, element 117, is also radioactive, alpha-decaying to an isotope of element 114. The chain of successive alpha decays continues until at least element 106.

source http://www.radiochemistry.org/periodictable/elements/117.html

this now obviously needs ammending - my chemical knowledge is a little basic so over to someone with better knowledge--Sumo su 21:06, 15 December 2006 (UTC)

There's something wrong with this article, as an element with number 118 should alpha decay to an element of 116 (Z-2) with mass (A-4). I cannot see how 118 can go to 117 by alpha decay. SBHarris 22:18, 15 December 2006 (UTC)
I'll bow to your superiour knowledge, as I say my chemistry is basic.

--Sumo su 22:45, 15 December 2006 (UTC)

[edit] Missing an element?

Insert formula here</math>Where is Lanthanum 57, and why is there an asteric where it should be —The preceding unsigned comment was added by Harbar1232 (talk • contribs) 19:09, 5 January 2007 (UTC).

[edit] Elements to 362

Does all 362 elements could exist or is it possible to make? If not, whats the highest possible atomic number or atomic mass? Cosmium 03:06, 27 January 2007 (UTC)

You might find "island of stability" interesting. — RJH (talk) 17:03, 22 February 2007 (UTC)

[edit] Hypothetical element name and superheavy elements

I made the hypothetical element names from beyond roentgenium to lajon (element 362). I made these hypothetical element names because I want to make the element names like regular names as in elements to 111 and makes me exciting instead of IUPAC Systematic element name. The same symbols for hypothetical element names will never be used more than once, not even once in every block. I used the three letter symbol for some elements only beyond element 218 if necessary. The examples of hypothetical names by atomic number are daltonium (Dt) for element 114, wakine (Wa) for element 117, plantium (Pl) for element 119, cosmium (Ao) for element 122, kritonium (Kt) for element 126, adrianium (An) for element 140, helestine (Ht) for element 167, baron (Bn) for element 168, pacificium (Pf) for element 220, and aerium (Ae) for element 352. There is probability that I'm might phase out the hypothetical element names from 219-362, 221-362, 291-362, or any others. Those superheavy elements apparently does not exist because the element hydrogen is the lightest element, is the building block of all the element. The heavier the elements are, the more energy required for fusion process. But it will may not be caused by their nuclear instability. For example, some elements heavier than 118 could have stable isotopes. There might be another mass of stability as in elements from hydrogen to bismuth that could begin at element 164 (micronium) and possibly ends beyond element 218 (<240>). I'll might predict that periodic table with 362 elements could have three mass of stability and two mass of instability. In nature, elements can exist only up to element 98 (californium), heaviest element observed in supernova. However, these superheavy element greater than 218 could possibly exist in the universe produced by very violent hypernovas. An example is that violent hypernovas is so powerful that it could have enough energy to fuse four californium atoms to make element 384, which is heavier than element 362, and releases four helium nuclei. Such a event is very rare, probably it hasn't been occurred in our galaxy. If such a superheavy elements does exist in the universe, but not on Earth or Milky Way galaxy, then I will not phase out the hypothetical element names from 219-362 and possible I'll make more hypothetical names beyond 362. Alternatively, element 218-362 or more should be made in nuclear accelerator because they should study these elements including physical properties, and chemical properties, just like naturally occurring elements and may have some commercial uses. Cosmium 03:06, 27 January 2007 (UTC)

[edit] Most common elements in the Known Universe

Having more than a passing interest in astronomy, I find this unreferenced section somewhat troubling. This appears to be the proportions of elements found inside a galactic environment that has been enriched with metals (elements heavier than helium) through stellar evolution. However a considerable amount of chemical matter lies outside galaxies, and this is nearly all hydrogen and helium; the primordial abundances. So "Known Universe" seems like a misnomer. — RJH (talk) 16:37, 22 February 2007 (UTC)

I partly addressed this by some preliminary text and a {{Fact}} template. — RJH (talk) 17:02, 22 February 2007 (UTC)

[edit] Chemical elements found on Earth: answer is at least 94

Hi, please provide a source for this edit. My references state 92 naturally occuring elements. --Sadi Carnot 00:47, 2 March 2007 (UTC)

Perhaps there's a rule against for using wikipedia as its own source, but for stuff that's obvious, I don't think it's more than a simple problem of putting in the work to get a cite, which at this point I don't have. But there's no element up to Np (number 94 inclusive), which isn't found naturally on Earth, as you can see by reading the Wikis on all the elements with lower atomic numbers. So you can count, and the number is 94. I have no idea where the classical 92 number comes from in all the old books-- are they just mechanically going up to U and forgetting Tc and Pm? Or going up to Np and leaving out 43 and 61? Or maybe 85? and leaving in Tc or Pm? I dunno, and I don't care. But the number is 94. In the case of Np, it's found in trace amounts in U ores, having been formed by neutron capture. If you read down in the chemical elements article to the discovery section, it gives the 6 rarest ones on Earth, starting with the rarest, astatine, followed by Fr, then the others (Pm and Tc found first in stars but later verified naturally, and Pu-244 actually found pimordially). If you look up the individual Wikis on all these elements (start with astatine, where it's a major part of the interest) you'll see the details. Some are referenced, but if Isaac Asimov said it, you can google it. SBHarris 19:37, 2 March 2007 (UTC)
According to the 2004 Oxford Dictionary of Chemistry, there are “92 naturally occurring elements.” Likewise, the 2004 McGraw-Hill Concise Encyclopedia of Chemistry states that all elements with atomic numbers above 92 have been synthesized in a variety of man-made nuclear reactions. Google search results for “number of naturally occurring elements” likewise indicate 92 as the common answer. I would prefer exact sources and dominant views. Also, here's a link to the 83 that we can actually see. I will move this discussion to Talk:Chemical element where the change to "94" occured. --Sadi Carnot 20:05, 2 March 2007 (UTC)
I changed it back again to 92 with a reference. I you find a substantial reference clearly states that there are 94 naturally-occurring elements, feel free to add it. --Sadi Carnot 09:26, 3 March 2007 (UTC)

For some discussion about primordial plutonium, with references, see [[1]]. For information about non-primordial natural plutonium and other transuranic elements, see Oklo phenomenon. IMO, the 92 figure is just a factoid that gets repeated and repeated all over the place, even when most chemists know it's wrong or don't care. As far as most chemists are concerned, the number is < 92 for practical purposes, because some elements are only found in trace amounts (such as At, Tc, Pm, Fr). But being strict, the number is at least 94. I'll see if I can find a good solid reference. A dictionary is not a good reference for this topic, IMO. --Itub 09:36, 5 March 2007 (UTC)

See A. Earnshaw, Norman Greenwood. Chemistry of the Elements, Second Edition. Butterworth-Heinemann, 1997. It is a very well-respected advanced inorganic chemistry textbook, specializing in the elements, as the title suggests. Curiously, it doesn't seem to give a count for the number of "naturally occurring" elements (which agrees with my claim that chemists tend not to care too much about that piece of trivia). However, it does say that Np, Pu, Tc, and Pm are all naturally occurring, so it is trivial to conclude that the number according to this source is 94. --Itub 10:05, 5 March 2007 (UTC)

Also some books say 90 natural elements. While also incorrect, this number could be correct if we redefine "natural" to mean "originally discovered by humans in nature, rather than through artificial nuclear reactions". That number has the advantage that it will remain constant (assuming no historical reinterpretations), unlike the 94, which could easily increase with time. ;-) --Itub 10:25, 5 March 2007 (UTC)

Hmm...I was surprised to see 94 and not 92. Half life of neptunium 237 is around 2e6 years, and plutonium 242 around 3.5e5. All subsequent decay products have shorter half lives and these materials would not exist naturally on earth anymore. So, I think the question is really "naturally occurring in what sense?" We could mention this somewhere, but I don't think it is too important. --HappyCamper 04:26, 29 March 2007 (UTC)
But then again, there is plutonium 244. Maybe Itub is right after all :-) --HappyCamper 04:48, 29 March 2007 (UTC)
Neptunium, and plutonium-239 are formed naturally in uranium ores due to neutron absorption. Of course, the amounts are extremely tiny, but they have been detected. The difference in this case is that they are "natural" but not "primordial". --Itub 07:45, 20 April 2007 (UTC)

[edit] Definition is wrong

The lead paragraph says:

A chemical element, or element for short, is a pure substance that cannot be decomposed into any simpler substance.(ref:Boyle) Said another way, an "element" cannot be transformed into other chemical substances by chemical processes. The modern definition, as contrasted with the older four element theories, was introduced by Robert Boyle in 1661.

This definition should be confined to the history section. The current definition is, according to IUPAC,[2] "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." --Itub 09:59, 7 March 2007 (UTC)

Maybe wrong was too harsh, let's just call it "outdated". Anyway, I've done some bold changes to the article and fixed some other inaccuracies. --Itub 11:07, 7 March 2007 (UTC)

[edit] Plato's stoicheia in Greek alphabet

στοιχεῖα —The preceding unsigned comment was added by 85.206.196.230 (talk) 22:33, 21 April 2007 (UTC).

[edit] Plato's Timaeus

Plato associated the dodecahedron with the heavens in Timaeus, though he did not elaborate this part of his theory, and thus preceded Aristotle in adding a fifth element. CRATYLUS22 —Preceding unsigned comment added by 71.42.136.9 (talk) 07:40, 13 February 2008 (UTC)

[edit] Request

I'd like to request that this page cover the topic of how to isolate particular elements/isotopes through means such as mass spectrometry, freeze out, and atomic diffusion. This is on the to-do list for the atom article, but I think it is more applicable here (since the techniques vary by element and isotope). Thank you.—RJH (talk) 18:51, 4 January 2008 (UTC)

[edit] greater than 82

You state that elements greater than atomic number 82 are unstable (true), and that elements Bismuth and higher are unstable (false). Bismuth IS element 82, so how can both be true? Bismuth is not subject to radioactive decay. Please revise this, as I am unable to with the page's semi-protected status. -24.192.98.124 (talk) 22:05, 7 January 2008 (UTC)

Bismuth is element 83, not 82. And all isotopes of bismuth are subject to radioactive decay (see bismuth-209). So I think the article is correct. -- Ed (Edgar181) 23:58, 7 January 2008 (UTC)

[edit] Temperature distribution of phases of the elements

Do you have any use for this chart? --81.27.125.127 (talk) 21:25, 29 April 2008 (UTC)