Talk:Chemical compound

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Naming[edit]

What about naming chemical compounds? —The preceding unsigned comment was added by 70.36.61.40 (talkcontribs) 02:11, 20 December 2005 (UTC)

Someone needs to add a chart of some kind about naming the compounds. I can produce it if no one feels up to it TheSun 00:03, 29 August 2006 (UTC)
How can one group of compounds have so many functions????
Each compound has it uses. --Chemicalinterest (talk) 00:41, 8 September 2010 (UTC)

cool —Preceding unsigned comment added by 220.233.152.229 (talk) 02:55, 1 March 2011 (UTC)

Purity[edit]

Re: Dwarf King's entry about a compound being the most complex pure substance. I reworded his statement to hopefully make it more clear, but I'm not sure it's strictly correct, and I'm not sure it belongs in the article. In truth, I think some fleshing out might make it obviously worthy, but am not currently clear on just how to state it. The validity of the comment depends on the definition of 'purity' and so perhaps it doesn't belong. Be bold! Catbar (Brian Rock) 03:48, 22 November 2006 (UTC)

A compound IS a pure substance. The chemical definition of purity is that which consists of only 1 kind of representative particle, and a representative particle doesn't have to be a single atom. While a molecule has more than 1 atom (and of course a compound molecule has atoms of different atomic numbers), they share common valence electron orbitals. Therefore, a molecule is a single representative particle. The Mysterious El Willstro (talk) 01:05, 26 March 2010 (UTC)

Definition of a chemical compound[edit]

"... two or more elements chemically-bonded together in a fixed proportion by mass"

shouldn't the definition of a chemical compound rather be based on stoichiometry than on mass?

The substitution of one isotope for another one won't change the chemistry but certainly the mass proportion, so I think a definition based on mass is completely out of the reason. 130.238.197.120 11:56, 18 October 2007 (UTC)

I agree. Carl Kenner 14:34, 29 October 2007 (UTC)
==== H2, S8, N2, O3 are not compounds? What nonsense. Put in a DEFINITIVE reference to this silly claim. Hmph! :)
--I have removed
Not all molecules are compounds. A diatomic molecule of hydrogen, represented by H2, is homonuclear — made of atoms of only one element, so is not regarded as a compound.
Compounds are pure substances that contain two or more elements combined in a definite fixed proportion. this is not true
---because I believe it is wrong. I believe "chemical compound" is, BY DEFINITION, a substance which can not be further separated into constituents by physical means without breaking (or making) of covalent bonds. This definition obviously will have difficulties with isotopes, high polymers and ionic compounds. It is pragmatic and only serves a useful purpose in a limited number of contexts. Let us say it is an emergent property, rather than a fundamental property of a material.-------- on further consideration, this whole article is horrible. The definition is WRONG. Its is a feeble attempt to give a precise definition to a fuzzy concept. The problem is, doing so changes the nature of the concept. Some fuzzy concepts should remain so, their utility is severly degraded when cetain types try to steal a term and assign a more formal meaning (definition) to it.--
(NOTE: I've restored the above revision... which was never signed... to its original wording and format to clarify its meaning and to restore the talk page a little closer to its "pre-vandalized" state. I've also indented to clarify where each new entry in this section begins. -- edi(talk) 21:36, 17 April 2009 (UTC))
This has already been addressed in the article, but just for the sake of future discussion, here are some references that I consider pretty "definitive". Chemical compound(s) =
  1. a substance that contains "two types of atoms in fixed proportions" -- General Chemistry, 4th Edition. Hill, Petrucci, McCreary, & Perry. Pearson/Prentice Hall. 2005. p. 6.
  2. "a substance with constant composition that can be broken down into elements by chemical processes" [book's emphasis] -- Chemistry, 7th Edition. Zumdahl & Zumdahl. Houghton Mifflin Co. 2007. p. 27.
  3. "substances composed of two or more elements; they contain two or more kinds of atoms" -- Chemistry: The Central Science, 11th Edition/AP* Edition. Brown, LeMay, Bursten, & Murphy. Pearson/Prentice Hall. 2009. pp. 5-6.
  4. "substances that can be separated into simpler substances only by chemical means" -- Chemistry, 1st Edition. Wilbraham, Staley, Matta, & Waterman. Prentice Hall. 2002. p. 36.
  5. "a pure substance consisting of two or more different elements in a fixed ratio" -- General Chemistry, 6th Edition. Whitten, Davis, & Peck. Saunders College Publishing. 2000. p. 15.
  6. "a pure substance composed of two or more elements whose composition is constant" -- Random House Dictionary. "Compound" Random House, Inc. 2009.
  7. "A pure, macroscopically homogeneous substance consisting of atoms or ions of two or more different elements in definite proportions that cannot be separated by physical means" -- American Heritage Dictionary of the English Language, Fourth Edition. "Compound". Houghton Mifflin Company. 2006.
  8. "A union of two or more ingredients in definite proportions by weight, so combined as to form a distinct substance" -- Webster's Revised Unabridged Dictionary. "Compound". MICRA, Inc. 1998.
(NOTE: The chemistry textbooks listed above are books that I own. The general dictionary references were gathered from dictionary.com on 18 April 2009.)
It seems apparent to me that the general consensus definitely supports the idea that a compound must contain two or more elements. The few definitions that don't specifically mention this point (only Zumdahl and Wilbraham in the list above) also don't by any means rule out the idea that the compounds contain two or more elements. In fact,Zumdahl and Wilbraham strongly imply that such is the case; otherwise, how could it be "broken down into elements" (Zumdahl)? (Wilbraham's "separated into simpler substances" is slightly more vague, but seriously... what else could it really mean?)
The article does currently read "Chemical compounds are pure chemical substances consisting of two or more different chemical elements...", and that's great. But the statement is unsourced, so I'm going to attach the Hill, Brown, and Whitten books as references, leave this information here, and hope that the controversy doesn't arise again. Crossing my fingers... :) -- edi(talk) 15:43, 18 April 2009 (UTC)

Types of bonds[edit]

"The atoms in the molecule can be held together by bonds, covalent bonds or ionic bonds."

This originially was "...by no bonds,..." which also doesn't make sense. It's been a while since I took a chemistry class, but I thought there were three types of bonds: hydrogen bonds, covalent bonds, and ionic bonds. Can someone in the know please decipher what it should be? --Wizard191 (talk) 13:57, 14 March 2008 (UTC)

compounds are formed during a chemical reaction of two or more elements or two or more types of atoms. —Preceding unsigned comment added by 24.188.201.90 (talk) 20:47, 19 March 2009 (UTC)

Vandalism[edit]

I came here and noticed many instances of vandalism. ive proposed it be semi protected. i question the appropriateness of the section called "Elementary concepts", it doesnt seem like it fits here, is unrefed, and unfortunately was added by a questionable new user.Mercurywoodrose (talk) 15:36, 7 April 2010 (UTC)

Elementary Concepts[edit]

FTA: "Elements in a compound cannot be separated by physical methods." Isn't electrolysis a physical method of decomposing a substance ?

Removed - there are many (non-easy) ways of decomposing a solid into elements, for example by irradiating it with high-energy particles. Materialscientist (talk) 12:09, 1 April 2011 (UTC)

Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms? Say what?[edit]

If you go to chemical substance it says much the same thing. The problem is that this is true only part of the time (i.e. for only some types of compounds). Yes, some chemical substances and chemical compounds have fixed ratios of atoms held together by chemical bonds, but others do not, and yet are clearly NOT just mixtures. Atoms in a sample of matter may all be held together by ionic or covalent bonds, but they don't need to have (in fact usually do not have) neat empirical formulas you can write down on a bottle label. Most of the mantle and crust of our planet is such stuff--for example, the plagioclase feldspars which don't have clearly defined stoichiometry. These articles are all confused. The chemical compound article refers to chemical substances, and vice versa. We need to make it clear that whole-number stoichiometry sometimes happens, but usually it is just an ideal. Fixed ratios of atoms are the exception in nature, not the rule. SBHarris 06:43, 26 February 2012 (UTC)

Depends. Let's take binaries. In my practice, simple solids which can be made into nearly perfect crystals (say, proper quality III-V and I-VII materials like GaAs, NaCl, maybe SiC) are well stoichiometric, with deviations on the ppm level. Indeed, there are many classes which are intrinsically non-stoichiometric (borides, carbides, most II-VI compounds, etc.), but it is tricky to compare their significance - by production volume, abundance, importance? Nature is a poor reference because synthesis is much cleaner and more homogeneous in the lab. Materialscientist (talk) 07:20, 26 February 2012 (UTC)
But what other reference can we make but nature? This is not an article about chemical compounds and substanes one is likely to find in the lab-- it is about chemical compounds and substances, period. The definition it gives, should cover and include chemical subtances and compounds one encounters in nature and the world. We describe for the student what he or she will see. Q. what is the the nature of these chemical substances one finds in observing the world? Well, mostly what one finds, are not what is described in these articles! Air and water and (some of) biology, yes. The rest of the universe (a rather larger place), no! There is no point in inserting any artificial limitation here. The Wiki describes water and table salt, yawn. For dirt and rock and all the things my house, clothes, and computer is composed of, it does not. Indeed, it's hard to say that even my own body solids are more stoichiometric than not. Is my hair or any other of the chemical molecules or substances that compose my body, actually described by these articles on chemical compounds or sustances? No! They fail. SBHarris 08:30, 26 February 2012 (UTC)
On nature: for many compounds we have mirror articles, one on a chemical compound and another on the mineral of the same composition. Sometimes even more, like sodium chloride, halite and salt. Materialscientist (talk) 08:38, 26 February 2012 (UTC)
Sure, but for even more we do not. Why pretend? Most of our planet is not stoichiometric and has no more sure empirical formula than a "generic" histone or a starch molecule in a peach I'm eating, which might be the only ones with those methylation or branching patterns like them in the universe. This is not needed to be forced on this definition. SBHarris 08:57, 26 February 2012 (UTC)