Talk:Atom

Template:WP1.0

Picture of an atom

In your picture of the helium atom would it be possible to label the nucleons conseculatively 1,2 3, and 4, and then draw an arrow through each of the nucleons to show the spin orientation relationship?WFPMWFPM (talk) 18:30, 27 August 2008 (UTC) It would be really nice to have a real image of an atom. I know it is done, I even think I saw it in O'Hanian.

Are you referring to having an accurate diagram of an atom, or an image of an atom made from a Scanning tunneling microscope (or equivalent)? Iotha 02:53, 26 January 2007 (UTC)

"If an apple was magnified to the size of the Earth, then the atoms in the apple would be approximately the size of the original apple." - If satilites can view people from outer space, then surely we will soon have the technology to see the atoms in an apple? (Seb-Gibbs) —Preceding unsigned comment added by Seb-Gibbs (talk • contribs) 21:22, 23 January 2008 (UTC)

Atoms are smaller than the wavelength of visible light, so even if you had an unbelievably powerful microscope, it will always be impossible to see without special imaging techniques (that's why we use electron microscopes). 24.131.183.162 (talk) 17:39, 10 February 2008 (UTC) darkstaruav, 10 February, 2008

You can see a picture of a concept of the atomic nuclei on Talk:Nuclear model. WFPMWFPM (talk) 16:22, 17 May 2008 (UTC).WFPMWFPM (talk) 21:24, 27 May 2008 (UTC).WFPMWFPM (talk) 21:31, 27 May 2008 (UTC)

hey, i dont get why you would write 100k fm in the picture - it's meant to be accessible to anyone and a femtometer doesn't mean much to most people.. would be better to express it in millimeters, or even in nanometers, which most people have heard of i think (UTC) —Preceding unsigned comment added by Popffabrik (talk • contribs)

Question about image of atoms

In the article there is an image that is said to be a picture showing individual atoms, is this true? Does this picture actually show the atoms that make up that sheet of gold?

Sorry if this isnt the propper way of asking this, but I'm just dumbfounded by this, as far as my limited knowledge went, they hadnt been seen nor pictured in any form yet. 200.109.43.50 (talk) 01:09, 4 January 2008 (UTC)

Yes, images which represent atoms have been generated for several years. I think the probe is actually detecting the electric field of the atom's electrons at very close range, but I'd have to go read up on the technique to confirm that. The image is resolving things which are the size of atoms, whatever the technology is actually doing; it's equally amazing whether electrons, photons, or X-rays were being used to create the image. -- SEWilco (talk) 02:04, 4 January 2008 (UTC)

You're actually looking at a map of electron density (the probability that an electron exists in that location), not a 'snapshot' image of a physical surface (which, after all, doesn't really exist in the way a surface of a macroscopic ball exists) Furmanj (talk) 11:48, 4 January 2008 (UTC)

Nobody has an "Image" of an atom. What is available are images of concepts of atoms from which you are supposed to make your preference. We also have a set of "combined facts and/or opinions" which are the suggested criteria for making such a selection. While doing so, I suggest that you learn as much as you can about the physical events occurring in the volumes of space where atoms are being created. The most notable one I can find is the Hubble images of the center of the Whirlpool Galaxy (M51). If you want an image of a concept, I recommend that you look at Talk:Nuclear model WFPMWFPM (talk) 23:48, 14 May 2008 (UTC)WFPMWFPM (talk) 14:06, 15 May 2008 (UTC)WFPMWFPM (talk) 21:42, 27 May 2008 (UTC)

I'd like to talk here about the article's paragragh about Electron orbit energy levels. These are supposed to be occurring to the orbiting electrons in the electrostatic attractive field areas and involve a concept of the existence of a zero or free electron level from which the involved electron can fall into discrete levels of lost free energy or minus incremental energy values. The incremental units of these values are usually given in Electron volts, which is both an energy times time (erg-second) and an equivalent angular momentum (MVR) unit. In Bohr's original orbit theories the orbits were considered to have actual angular momentum magnitude values, but in the orbital theories no values of angular momentum are considered. And the radiation emissions are usually indicated as being emitted from the center of the atom. This obscures and damages the ability of a person to conceptualize as to how the atom is able to get rid of angular momentum and wuld indicate that some constituent of the atom, hopefully the electron should be retheorized in some manner to allow it to emit radiation at the end of a lever arm, vis a vis the whip principal or whatever. If you'll look at my pictures of real physical nuclear models((Talk:Nuclear model)) you'll see that I had gotten as far as that question in the models, but not far enough to answer the question. But I think it's a worthy subject for discussion in your discussion about Orbital electron energy levels in your evolving artical about the atom.WFPMWFPM (talk) 21:49, 20 August 2008 (UTC)WFPMWFPM (talk) 14:59, 21 August 2008 (UTC)

If I may attempt to jump to the crux of your discussion, you seem to be saying that there is a concern about radiation emissions being perceived as coming from the nucleus, rather than from the decaying electron. The article states that, "In order for an electron to transition between two different states, it must absorb or emit a photon at an energy matching the difference in the potential energy of those levels." This would not seem to agree with your assertion.—RJH (talk) 18:57, 21 August 2008 (UTC)

I Just guess that I cant concieve of a kind of physical motion of the electron that isnt some kind of radial motion involving a conic radial orbit with constant angular momentum and a constant value of lost potential energy. And if the electron was causing the emission of some of the mass of the atom in the form of radiation particles or radiation waves as goes the theory then a reasonabally correct description of the electron's motion would be desirable for conceptual purposes. And I think it would involve an orbit with a conserved amount of angular momentum. WFPMWFPM (talk) 21:08, 21 August 2008 (UTC)

It sounds like you mean the Bohr model of the atom.—RJH (talk) 18:39, 25 August 2008 (UTC)

Another aspect of this radiation concept problem has to do with what might be called compartmentalism of concepts. So when discussing radiation from the atom it may me adequate to just discuss energy difference values. But when you want to discuss radiation from the center of the ((Whirlpool Galaxy)) you get involved with whether or not the emitted radiation is carrying off some of the observed excess angular momentum in the system as some scientists think it does. And so the process of radiation from matter in that system in terms of MVR change values rather than MVsquared values would have to be conceptually discussed.WFPM66.139.107.38 (talk) 16:52, 22 August 2008 (UTC)WFPMWFPM (talk) 16:59, 22 August 2008 (UTC)

This is getting decidely off topic, so I'll leave off.—RJH (talk) 18:39, 25 August 2008 (UTC)

I might even add to that the problem in or own solar system where the sun has managed to acquire 99+ percent of the matter of the original solar gas system but now has only a small portion of of the system's angular momentum.WFPMWFPM (talk) 16:18, 26 August 2008 (UTC)

Again, this is off topic. I would probably be best to discuss this matter at the Wikipedia:Reference_desk/Science. Thank you.—RJH (talk) 22:50, 1 September 2008 (UTC)

Number of atoms in the Universe

I'm having a little difficulty trying to solidify this value, so I moved it here for the moment. The estimates fluctuate depending on the author and I can't find a really solid scientific paper on the topic. Here are some examples:

Number of atoms in the observable universe

Value	Reference
1079	"The Universe". National Solar Observatory. May 21, 2001. Retrieved 2008-02-15. {{cite web}}: Check date values in: |date= (help)
1080	Champion, Matthew (September 11, 1998). "How many atoms make up the universe?". MadSci Network. Retrieved 2007-01-02. {{cite web}}: Check date values in: |date= (help)
1081	deGrasse Tyson, Neil (1994). Universe Down to Earth. Columbia University Press. pp. p. 10. ISBN 023107560X. {{cite book}}: |pages= has extra text (help)

Any suggestions? Thanks.—RJH (talk) 17:29, 15 February 2008 (UTC)

Expansion of the universe? Seriously, it's a problem. First, we should qualify that we're talking only about the visible universe, because the part over the horizon is probably a lot larger, and Travelocity rates to get there are steep. But once you get the mass of the visible part down (which should be derivable from the expansion rate), you subtract dark matter (since not made of atoms), and them divide the rest by the average molecular weight of post big bang "crap", which at one He per 12 H is about 2e27 atoms per kg or so, right? SBHarris 18:07, 15 February 2008 (UTC)

I understand how it is derived and what is meant by the visible universe. What is needed is a bullet-proof reference.—RJH (talk) 19:12, 15 February 2008 (UTC)

The size and density of the observable universe were only really pinned down in this century, with the current best data from WMAP. So all these references are out of date. I could derive the number from the data given in the WMAP papers, but it would be WP:original research ;) 140.105.79.118 (talk) 15:54, 15 May 2008 (UTC)

Given the sun's mass at 10E33.3 grams times 10E23.8 nucleons/gram we get 10E57.1 nucleons/sun. Then if we buy the 10E11suns/galaxy and 10E11galaxies/universe theories, we get 10E79.1 nucleons/universe; plus whatever amount of unknown matter you want to add. But I think we ought to start out with a large amount of neutrons. Like maybe 90%?WFPMWFPM (talk) 02:00, 17 June 2008 (UTC)WFPMWFPM (talk) 19:11, 17 June 2008 (UTC)

Don't forget interstellar and intergalactic matter, which are significant contributors.—RJH (talk) 15:48, 22 June 2008 (UTC)

Kind of depends on which physical problem you're worried about? Galactic rotation? or Red Shift? or what? WFPMWFPM (talk) 02:29, 24 June 2008 (UTC)

Nicastro et al (2008) has some interesting observations on the distribution of baryonic matter under the standard cosmological model. At least half of the baryonic matter is currently thought to be in the intergalactic medium.—RJH (talk) 16:33, 24 June 2008 (UTC)

Is that matter what we're looking at in the center of the whirlpool galaxy? What I see is matter with a lot of excess angular momentum. And how are we supposed to gid rid of that?WFPMWFPM (talk) 13:12, 27 June 2008 (UTC)

Here you seem to be straying off topic. Later.—RJH (talk) 15:18, 27 June 2008 (UTC)

The topic of the article is atoms, and the picture of the center of M51 appears to me to be one of the best in showing the environment in which the process of accumulating matter into atoms is occurring, and I really would like to understand the process, like the matter recipe and how the system is getting rid of what appears to be excess angular momentum. And after all the universe is theorized to be made up of approximately 10E11 of these or similar galaxies. and they just recently discovered a supernova in M51. So if we could explain the recipe and process in it we would be well on our way to understanding the processes of the universe at large. WFPMWFPM (talk) 23:02, 27 June 2008 (UTC)

M51 is a planar galaxy and the constituent components are moving primarily under the influence of gravity, including density waves. To claim that it bears a close likeness to an atom is to ignore the fundamental differences between electricity and gravity, and to toss out the well established phenomenon of quantum mechanics. I'll have to disagree.—RJH (talk) 19:01, 21 August 2008 (UTC)

==It is interesting to note that the article starts of about atoms as if they were either the or among the most important constituent parts of the group of entities making up the "Real Physical Universe" It is only deep into a discussion of their "origin" and conjectural details that it estimated that their mass percentage is around 4 percent of the total. Thus the concept that the "atoms" are a "minor?" part of a matter accumulation process being carried out by nature is overlooked. And their place in the hierarchy of the entities of matter is described but not organized until you get to "Universe Origination" theories where controversial details are discussed in more detail but not with much organizational clarity. For example in this section, Universe quantities of Atoms are talked about, when the question is evidently about nucleons. An explanation of the relative importance of "atoms" to the rest of the hierarchy might be helpful even in this "Atom" article. WFPMWFPM (talk) 23:46, 18 October 2008 (UTC)

completely stable

What do you mean by completely stable in "The heaviest completely stable atom is that of lead-208"? Don't all atoms have a limited lifetime (although some are indeed quite long)? Randomblue (talk) 18:46, 15 February 2008 (UTC)

A stable element has at least one stable isotope. I added a wikilink.—RJH (talk) 19:05, 15 February 2008 (UTC)

Although in some theories protons decay, this has never been proven. Until it is, so far as we can tell, stable isotopes are stable forever.SBHarris 03:22, 12 May 2008 (UTC)

edit to intro

I removed the statement that the wave-particle duality was used to model the atom. Though it takes no stretch of the imagination that the two are related, the statement is vague. The sentence that remains is clear and sufficient. Also I removed the reference Harrison (2003). Without a title or a publisher this could be any of a hundred articles os books. --V. (talk) 05:03, 13 May 2008 (UTC)

The Harrison reference refers to the book cited at the bottom of the article, in the "Book references" section: Harrison, Edward Robert (2003). Masks of the Universe: Changing Ideas on the Nature of the Cosmos. Cambridge University Press. ISBN 0521773512. --Itub (talk) 08:53, 13 May 2008 (UTC)

is there a specific reason that the books are separate? --V. (talk) 18:34, 13 May 2008 (UTC)

I didn't do it, but my guess is that this method is used because it allows one to have several references to different pages of the same book without excessive duplication and without using "ibid" and such. For example, ref 1 might say "Harrison (2003), p 42" and ref. 2 might say "Harrison (2003), p 89". But I don't see any book citation in this article with page number, so the separation is not really justified IMO. --Itub (talk) 18:51, 13 May 2008 (UTC)

The separation of the books into a list was requested as part of the FA candidate edits. A reviewer wanted a list that they could easily read through. (See Nigel, Wikipedia:Featured article candidates/Atom.) The reference is to the book list on this page and is unambiguous, so I restored it. If the issue is with the lack of page numbers, I can work on adding them in where appropriate.—RJH (talk) 22:26, 13 May 2008 (UTC)

There are other strange and vauge statements here. To describe the atom as the smallest particle in a chemical element is simply wrong. You might seek to say that you don't need to go any smaller to talk about chemistry, but the oxidation states of atoms depend on electron transfer, and this underpins much of chemistry. Really, an atom is not the smallest particle in anything. I dislkie the use of term electron cloud, also. I know it's due to Feynman, and I don't discourage its use in the correct circumstances, but it's an analogy to the behaviour of electrons. To say that an atom is a nucleus surrounded by an electron cloud is to assert something false about the fundamental nature of electrons.—Che Gannarelli (talk) 09:58, 9 July 2008 (UTC)

You raise some interesting points. The chemical element describes it as a type of atom; if it is false here, then that article would also seem to be in error. The term "electron cloud" seems like a useful and colorful descriptor for readers that are unfamiliar with quantum mechanics. The behavior is clarified down in the text and on the electron cloud page. I'm not sure I see the harm.—RJH (talk) 17:54, 11 July 2008 (UTC)

I agree that describing the atoms as, "the smallest particle that constitutes a chemical element", is incorrect, or at least misleading. All atoms are chemical elements and all chemical elements are atoms (they are not, of course, synonyms as different isotopes are different atoms but are still the same chemical element). I think there needs to be a balance between rigorous correctness and good intuitive explanation, but I don't think this sentence can be justified either way (someone not familiar with the concept of an atom is probably even less familiar with chemical elements). I propose something along the lines of:

“ The atom is the smallest building block of ordinary matter, that is the gases, liquids and solids that comprise the macroscopic world in which we live. ”

The specific point this sentence is making is that although atoms are composed of smaller parts, these components cannot themselves form large-scale structures. In addition this sentence immediately makes the connection between atoms and the familiar materials around us. I realize a lot of work has gone into this article and I agree that it is worthy of featured article status, but I think this point needs to be addressed. I would appreciate any comments, alternative suggestions, or counter arguments.--DJIndica (talk) 13:07, 15 July 2008 (UTC)

I wasn't necessarily agreeing that the statement was false; only that if it is false then it would have to be false in both locations. The statement about atoms forming the smallest particle of a chemical element seems fine to me. Your proposed revision, on the other hand, is a little more debatable. You are introducing the vague notion of "ordinary" matter. Unfortunately, much of matter in the Universe is plasma, so one might consider that ordinary matter.—RJH (talk) 14:47, 15 July 2008 (UTC)

I think DJ's proposed revision is excellent. It is short, snappy, to the point and accurate. The 'vagueness' of 'ordinary matter' is not the problem. At the start of any Wikipedia article, generalities are stated first. Of course, scientific articles in particular must be accurate, but using 'ordinary matter' in the sentence is clear enough. If need be, 'non-ordinary matter' can be mentioned later on to clarify the difference. Also, I don't think plasma counts as 'ordinary matter' because the Universe contains a lot of it (cf. dark matter is the most abundant type of matter in the universe, but one clearly cannot describe it as 'ordinary matter' !!!). DJ's revision is a huge improvement over the status quo and therefore I believe it should be incorporated into the article. Thanks. :) MP ^{(talk•contribs)} 19:32, 15 July 2008 (UTC)

Scientifically, ordinary matter is considered baryonic matter, so this would include plasma. But no matter; it's clear enough.—RJH (talk) 21:30, 15 July 2008 (UTC)

It's a fair point that much of the matter in the Universe is not the "ordinary matter" this sentence refers to, but I think it is important, in the introduction at least, to make the point the much of the material we are familiar with from everyday life is made of atoms (and the rest is made of molecules which are themselves made of atoms). The first sentence needs to give an intuitive working definition of the atom for people not familiar with the concept; people knowledgable enough to debate whether baryonic matter inc. plasma or dark matter is more "ordinary" are not those the first sentence is aimed at. For a definition to be useful, it has to relate the new concept to something with which the reader is already familiar.--DJIndica (talk) 18:07, 16 July 2008 (UTC)

Like I said, it's clear enough. One might quibble with the use of the statement "building block", as some gases consist of individual atoms (neon, argon, &c.). Otherwise it's probably close to okay.—RJH (talk) 21:23, 16 July 2008 (UTC)

I had another go at clarifying this, as discribed at the bottom of the page, but it has been rather curtly reverted by User:Rracecarr, who declined to describe why he didn't "think this ... an improvement". The issue of inaccuracy is something I discuss at length at the bottom. Essentially, there are no independet atoms in covalent matter. The Britannica's description of an atom as the smallest uncharged unit of ordinary matter is about as simple as one can get while still being true. We need some intellegent discussion about this, rather than curt reverts. Che Gannarelli (talk) 15:52, 17 July 2008 (UTC)

Encyclopaedia Britannica

The 9th edition of the EB has two very informative articles about the Atom and the theory of the force of universal gravitational attraction by Prof. G Clerk Maxwell (Atom & Attraction) that explain the development of the classical concepts related to this subject matter. They are very much worthy of review and consideration. WFPMWFPM (talk) 23:18, 14 May 2008 (UTC)

(O/T NOTE: I fixed the format of your additions by placing it at the end, removing the blank from the start of the lines and moving the comments to a separate line from the section title. Please take a look at Help:Contents/Editing Wikipedia for more information on how to edit wikipedia. Thank you.—RJH (talk) 15:04, 15 May 2008 (UTC))

Proposed Czech image

An anonymous poster made the suggestion that we use the image at right as it uses a radial decay proportional to e^-r for the electron cloud. Is there interest in using this image in place of the current helium atom diagram? I'm not sure whether the listed units are best for this purpose.—RJH (talk) 17:15, 16 May 2008 (UTC)

I am not sure that He follows this law. Ruslik (talk) 08:23, 17 May 2008 (UTC)

Kindly clarify.—RJH (talk) 16:50, 18 May 2008 (UTC)

Electron density in He does not folllow e^-r law. Ruslik (talk) 11:12, 20 May 2008 (UTC)

Thank you.—RJH (talk) 15:06, 21 May 2008 (UTC)

Unsourced additions

The following additions, while probably correct, are also unsourced. To avoid a FAR, I would like to make sure that this page continues to satisfy the FA criteria.

Of the chemical elements, 80 have one or more stable isotopes (elements 43, 61, and all elements numbered 83 or higher have no stable isotopes). As a rule, there is, for each atomic number (each element) only a handful of stable isotopes, the average being 3.4 stable isotopes per element which has any stable isotopes. Sixteen elements have only a single stable isotope, while the largest number of stable isotopes observed for any element is ten (for the element tin).

Stability of isotopes is affected by the ratio of protons to neutrons, and also by presence of certain "magic numbers" of neutrons or protons which represent closed and filled quantum shells. Of the 269 known stable nuclides, only four have both an odd number of protons and odd number of neutrons are known: ²H, ⁶Li, ¹⁰B, ¹⁴N. Also, a very very long-lived radioactive odd-odd nuclides (⁴⁰K, ⁵⁰V, ¹³⁸La, ^180mTa) occur naturally. Most odd-odd nuclei are highly unstable with respect to beta decay, because the decay products are even-even, and are therefore more strongly bound, due to nuclear pairing effects.

It is often far easier to remove unsourced entries than it is to try and source somebody else's input, so I am hoping that citations are readily available for this material. Otherwise I think this should be pruned back. Thoughts?—RJH (talk) 15:30, 23 May 2008 (UTC)

The first paragraph can be sourced to the chart of the nuclides as it contains just trivial counting. The second one is more analytic but I'm sure can be based on any nuclear chemistry/physics book. --Itub (talk) 16:06, 23 May 2008 (UTC)

Perhaps then the CRC Handbook of Chemistry & Physics will cover both? It looks like the Table of Isotopes includes suitable information, so I'll just use that unless somebody squawks. Thanks. The only problem remaining is the use of "very very long-lived", which conflicts with Wikipedia:MoS#Unnecessary_vagueness. (Very very long-lived is 100 years to me...)—RJH (talk)

We could say "with a half-life of billions of years", or something like that. I know that's the case for K-40; I'd have to check the others. --Itub (talk) 18:02, 23 May 2008 (UTC)

Yes they're all over a billion. I think it's fixed now. Thank you.—RJH (talk) 18:04, 23 May 2008 (UTC)

First paragraph

There's some kind of glitch in the last sentence of the first paragraph: the grammatical construction's wrong, the content seems redundant given the previous content, and there are a couple of stray characters at the end.

Paul Magnussen (talk) 15:38, 9 July 2008 (UTC)

Fixed. SBHarris 20:02, 9 July 2008 (UTC)

African?

Smallest recognized division of a chemical element

"Classification Smallest recognized division of a 'african'"

I'm not sure of what this refers to...'african' links to Africa, and although I am sure that quarks are a smaller division of Africa than an atom, I don't think this is what was intended to be discussed.

Buteo lineatus (talk) 19:59, 9 July 2008 (UTC)

Issue has been resolved. Previously, "chemical element" was "african," but this has been remedied.

Buteo lineatus (talk) 20:00, 9 July 2008 (UTC)

Problem in intro

• The sentence

  A chemical element is determined entirely by the type of atom it contains, which in turn is determined by the number of protons, electrons and neutrons that constitute the atom.

  taken from the intro, is totally wrong. The only thing that determine the type of an atom is the number of protons. Turiacus (talk) 22:34, 9 July 2008 (UTC)

The new intro fixes that. It is much better than the old one. Great Job ! Turiacus (talk) 20:08, 14 July 2008 (UTC)

• You're right. The text was incorrect. I'd added it myself, and it was sloppy. It was in fact my attempt at a re-wording to remove the following line, now restored: "The atom is the smallest particle that constitutes a chemical element". I still feel that statement to be simply incorrect (as was my own). A chemical element is no less constituted of smaller particles simply because they are arranged into atoms. Furthermore, as electrons are transferred and shared in bonding, it is inaccurate in an important way, and not merely a strict sense, to say that atoms are the smallest constituents of an element; they're not even the smallest important constituents.
  
  Lastly, please note the above section on "First paragraph". This has all been discussed.Che Gannarelli (talk) 00:57, 15 July 2008 (UTC)

• Sorry, but your logic seems flawed. The fact that both atoms and chemical elements are composed of still smaller particles is essentially irrelevant to the assertion. The exchange of electrons are important in chemical reactions, true, but this is not a statement about chemical reactions. Since you can not form a chemical element solely out of independent subatomic particles, it is a true statement that the atom is the smallest "particle" that constitutes a chemical element.—RJH (talk) 14:41, 15 July 2008 (UTC)

• Ordinary matter is made of atoms, ions, or molecules. The second of these differs from the definition of an atom by the presence or absence of an electron, and the third, in the strong covalency regime, contains nothing that can be described as an individual atom. The statement is therefore palpably false; an atom is simply not the smallest particle of anything.

Britannica has a nice definition in the opening of their article "atom (matter)", by the way, which may indicate that they were agonizing over the difficulties of this, also. They state that an atom is the smallest unit into which matter may be divided without the release of charged particles. It's a more complex statement than the first, certainly, but it is at least true. I can't readily come up with a simpler, and accurate, introduction to the idea, I'm afraid. Che Gannarelli (talk) —Preceding comment was added at 15:20, 17 July 2008 (UTC)

• Consider: An atom is the smallest unit of an element that retains the chemical properties of that element. However, I do see an issue with ions -- they too might also qualify as "retaining chemical properties". Britannica's def also has an issue with ions. However, "The atom is the smallest building block of ordinary matter" just will not do - it would depend upon what the supposed "builder" chooses to start with. As far as I know, nobody has ever "built" an atom. Additionally, according to Big Bang theory, elements were "built up" out of smaller particles than atoms --JimWae (talk) 16:01, 17 July 2008 (UTC)

• Let's not over-complicate things. No reason to bring in cosmology. Just need a statement that's as simple as possible without being untrue. This really is a minefield! By the way, I chopped out the "solids, liquids and gases" bit because colloids, liquid crystals and so forth all fall within the pervue of this discussion. A common term for the type of "ordinary" matter we're referring to (excluding plasmas, and weirder things) is "atomic matter", but that's getting circular, and makes me want to put a cold towel on my head! —Preceding unsigned comment added by Cmsg (talk • contribs) 16:09, 17 July 2008 (UTC)

• If we need cosmology, we need it - at least here on the talk pages. "The atom is the smallest possible uncharged unit of ordinary matter" also does not do the job. Neutrons would qualify as uncharged - so unless you stipulate what ordinary matter is - which gets back to elements - there's a problem. Stipulative definitions are the bane of scientific writing--JimWae (talk) 16:14, 17 July 2008 (UTC)

• If you want to go with the simplest definition and most accurate definition, an atom is a group of one or more protons, with zero or more bounded neutrons, and with zero or more bounded electrons.
  
  A bunch of 7 protons and a neutron together is ⁸
  ₇N⁷⁺
  (Nitrogen-8 ionized 7 times, which would be unstable as hell). A bunch of 1 proton and 245 neutrons with a bounded electron would be ²⁴⁶
  ₁H⁰
  (again insanely unstable). Saner examples would be ionized tritium ³
  ₁H¹⁺
  and unionized carbon-13 ¹³
  ₆H⁰
  .

So for recap:

Z	Number of protons	Decides the "element"
N	Number of neutrons	Decides the "isotope" of the element
ne	Number of electrons	Decides the "ion" of the isotope of the element

Headbomb {ταλκ – WP Physics: PotW} 16:36, 17 July 2008 (UTC)

• Okay, let me have a go at stating what we're trying to convey. Then we'll find a form of words.

1) Ordinary matter, such as we all understand what we mean by that, is made up of either atoms, ions, or covalent molecules (possibly macroscopic), in which atoms have no individual identity (although ionic cores, comprising a nucleus and those electrons not involved in covalency, do retain their identity).

2) We want some kind of idea of smallest, because that's important to the definition of an atom, and yet getting a decent form of words for that is hard.

3) Whatever form of words is employed should seek to render your point about neutrons moot. "Ordinary matter" may not be divisible into atoms in the simplest sense of that description, but nuclei at least retain their identity. The real bonding process involve entities such as nuclei + electrons, or tightly-bound core ions + bonding-involved valence electrons.

So. The idea of "smallest significant constituent" (in the sense that protons, neutrons and core electrons don't do anything independent of atomic cores) is important. Yet the idea of neutral charge is also significant, for an atom is an important entity for exactly the reason that while it may not be the fundamental unit of ordinary matter, if you take electrons off one of them, it becomes charged.

I know how I'd describe this to a class: electrons are involved in bonding. An atom is defined in the non-chemical bonding limit. Start with the idea of an elemental gas, and state that it's not as simple as that when atoms coalesce. However, that's not a nice brief statement of what an atom is, suitable for this context.

This is going to wind me up no end. Off to find some books on solid state physics and atomic physics. Hope somebody has a flash of genius. Che Gannarelli (talk) 16:43, 17 July 2008 (UTC)

• Headbomb: you beat me to the chase. I think that the difficulty with simply listing the constituants of an atom, is that you're really saying nothing about physics. That's point 4), I suppose, and really the hardest of all: encapsulate at least a hint of why an atom is something physically important, and not just a way of counting subatomic particles. Che Gannarelli (talk) 16:43, 17 July 2008 (UTC)

• I don't like the introductory sentence "The atom is the smallest possible uncharged unit of ordinary matter." I see several problems with this. For starters, what about neutrons? Are they not ordinary matter? Rracecarr (talk) 17:46, 17 July 2008 (UTC)

• Nor do I. Consider: An atom is the smallest uncharged unit of an element that retains the chemical properties of that element -- possibly add and can participate in a chemical reaction. This eliminates ions. No need for "possible" which can easily be misread as meaning "possibly"--JimWae (talk) 17:55, 17 July 2008 (UTC)

• That seems good. I don't understand all the fuss about charge though. I always thought an ion is a charged atom--different number of electrons, but it's still an atom. Am I wrong about this definition? If so, is there a source showing that? If I'm not wrong, why not eliminate "uncharged", and go with An atom is the smallest unit of an element that retains the chemical properties of that element? Rracecarr (talk) 17:59, 17 July 2008 (UTC)

• I like that very much, Rracecarr. Encapsulates nicely the idea that it's no longer that element, once you go below the level of the atom. Glad to not worry about this one any more. Che Gannarelli (talk) 18:13, 17 July 2008 (UTC)

• Cool, done. Rracecarr (talk) 18:22, 17 July 2008 (UTC)

Proposed lead top-down re-write

• While it's better than what used to be there, I feel the prose is kinda weak and things seems to be introduced from the top-down rather than in a bottom-up approach. How about this version instead?
  

While the atom was first conceptualized as an indivisible component of matter by early Indian and Greek philosophers, the modern understanding of the atom is that it is a small agglomeration of protons, neutrons, and electrons, ranging from a tenth of a nanometer to a few nanometers wide. A definition often encountered in introduction-level chemistry textbooks is that an atom is the smallest unit of a chemical element that retains the properties of that element. In the 17th and 18th centuries, chemists provided a physical basis for this idea by showing that certain substances could not be further broken down by chemical methods. During the late 19th and early 20th centuries, physicists discovered subatomic components and structure inside the atom (protons, neutrons, and electrons), thereby demonstrating that the 'atom' was not indivisible.

Atoms have very small nuclei (about a few femtometers wide) made of protons and neutrons (also called nucleons), containing most of their mass (over 99.9%), with electron clouds surrounding them. Atoms are classified into elements (depending on the number of protons), isotopes (depending on the number of neutrons), and ions (depending on the number of electrons). Atoms with too many or too few neutrons relative to the number of protons are unstable and subject to radioactive decay.

Electrons are responsible for most of the chemical and physical properties of atoms. They occupy sets of stable energy levels, or orbitals, and can move between them by absorbing or emitting photons that match the energy differences between the levels. Classical models of electron behaviour in atoms include the plum-pudding model, the Bohr model, and the Rutherford model (amongst others), while quantum models includes the Sommerfeld model, and the Schrodinger model (amongst others).

Headbomb {ταλκ – WP Physics: PotW} 02:06, 18 July 2008 (UTC)

I think that's possibly a much better approach. A top down introduction is great, and the historical approach avoids the obvious danger of making simple but untrue statements. Che Gannarelli (talk) 09:50, 18 July 2008 (UTC)

Sorry but I have to strongly disagree with this proposal. It is important to define the subject matter in the first paragraph. This alternative approach seems meandering.—RJH (talk) 15:16, 18 July 2008 (UTC)

Well bringing history after definition breaks the flow, which is also important. Headbomb {ταλκ – WP Physics: PotW} 19:44, 18 July 2008 (UTC)

Per Wikipedia:Lead section, "The first paragraph needs to unambiguously define the topic for the reader." The proposed re-ordering moves that down to the second paragraph, leaving the reader dangling. Sorry, but I remain opposed, and I do not at all believe the flow is being broken.—RJH (talk) 19:49, 18 July 2008 (UTC)

Okay I reworded things. How about now?

I don't like starting with history. Leads should start with a definition, like RJHall says. Your proposed lead would work better for the article on History of atomic theory. --Itub (talk) 07:22, 19 July 2008 (UTC)

Agree with RJH and Itub. The lead must contain an overview of the subject matter, then the article should gradually get more technical. MP ^{(talk•contribs)} 09:34, 19 July 2008 (UTC)

But it does start with the definition... Headbomb {ταλκ – WP Physics: PotW} 11:38, 19 July 2008 (UTC)

From past experience, if this were going through FAC now, the number of parentheses would also be an issue. (Some web page scanners for the sight impaired apparently don't handle parentheses well.) In this case they also break the flow somewhat. Sorry.—RJH (talk) 23:10, 19 July 2008 (UTC)

The thing that fascinates me about encyclopaedic approaches to studies about physical entities is that our egocentric bias makes us miss the basic question, which what is the logic controlling the entities and the processes in the first place. And the logic of atoms is that nature has created a process of reaccumulating difuse matter that it have previously difused for some purpose in the first place, and what are the significant details of that accumulating process. So we start with difuse matter (or energy if you like), and then after phase 1 have a lot of nucleons (or energy packages], and these are accumuleted into atom package, and behind that we have a large package of matter (energy) waiting to gobble the whole thing all up (phase 3} and the question is, What are the controling factors in that process? And when are we going to get around to discussing that? WFPMWFPM (talk) 13:34, 1 September 2008 (UTC) And so, if we examine the logic of the process of accumulation of matter (energy) we see that nature first created matter (energy), then created a reaccumulation process, which incidently increases factorially as a function of the number of units of mass (energy) versus the direct one to one relationship of mass-energy creation. Then how could nature fail to be able to reaccumulate the difuse matter (energy) and defeat the original purpose? And do you have an article on this? WFPMWFPM (talk) 14:11, 1 September 2008 (UTC)

Oct 1 2006 version still has merit

http://en.wikipedia.org/w/index.php?title=Atom&oldid=78921569 still has info that needs to be included in current version --JimWae (talk) 19:33, 17 July 2008 (UTC)

Comparison & contrast with molecules needs to come much sooner in current version(is it even included?) --JimWae (talk) 19:49, 17 July 2008 (UTC)

In chemistry and physics, an atom (Greek ἄτομος or átomos meaning "indivisible") is the smallest possible particle of a chemical element that retains its chemical properties. The word atom originally meant the smallest possible indivisible particle, but after the term came to have a specific meaning in science, atoms were found to be divisible and composed of smaller subatomic particles.
Most atoms are composed of three types of subatomic particles which govern their external properties:

• electrons, which have a negative charge and are the least massive of the three;
• protons, which have a positive charge and are about 1836 times more massive than electrons; and
• neutrons, which have no charge and are about 1839 times more massive than electrons.

Protons and neutrons make up a dense, massive atomic nucleus, and are collectively called nucleons. The electrons form the much larger electron cloud surrounding the nucleus.
Atoms can differ in the number of each of the subatomic particles they contain. Atoms of the same element have the same number of protons (called the atomic number). Within a single element, the number of neutrons may vary, determining the isotope of that element. The number of electrons associated with an atom is most easily changed, due to the lower energy of binding of electrons. The number of protons (and neutrons) in the atomic nucleus may also change, via nuclear fusion, nuclear fission or radioactive decay, in which case the atom is no longer the same element it was.
Atoms are electrically neutral if they have an equal number of protons and electrons. Atoms which have either a deficit or a surplus of electrons are called ions. Electrons that are furthest from the nucleus may be transferred to other nearby atoms or shared between atoms. By this mechanism atoms are able to bond into molecules and other types of chemical compounds like ionic and covalent network crystals.
Atoms ... are conserved in chemical reactions.

Atoms and molecules

For gases and certain molecular liquids and solids (such as water and sugar), molecules are the smallest division of matter which retains chemical properties; however, there are also many solids and liquids which are made of atoms, but do not contain discrete molecules (such as salts, rocks, and liquid and solid metals). Thus, while molecules are common on Earth (making up all of the atmosphere and most of the oceans), most of the mass of the Earth (much of the crust, and all of the mantle and core) is not made of identifiable molecules, but rather represents atomic matter in other arrangments, all of which which lack the particular type of small-scale order that is associated with molecules.
Most molecules are made up of multiple atoms; for example, a molecule of water is a combination of two hydrogen atoms and one oxygen atom. The term "molecule" in gases has been used as a synonym for the fundamental particles of the gas, whatever their structure. This definition results in a few types of gases (for example inert elements that do not form compounds, such as helium), having "molecules" consisting of only a single atom.

Why?—RJH (talk)

Because understanding the difference between atoms & molecules it key to understanding both concepts. Understanding how atoms can combine is part of understanding what atoms are --JimWae (talk) 21:42, 17 July 2008 (UTC)

This article is about atoms and that should be the primary focus. By earlier consensus during the review process, molecules and chemistry were de-emphasized in this article.—RJH (talk) 21:59, 17 July 2008 (UTC)

Disagree about the "halting & clunky". That's your POV. I'd say pointed & specific - it takes time to talk about each topic rather than trying to cover too may topics at once (sweeping & vague) - and thereby even needing to repeat itself --JimWae (talk) 21:42, 17 July 2008 (UTC)

Article has been through a Featured Article review where the lead was deemed acceptible by multiple reviewers. I reverted to the old form as your revisions are personal preference. Please discuss the change to gain consensus first. Thank you.—RJH (talk) 21:55, 17 July 2008 (UTC)

AcceptAble or not, does not mean it does not need improvement. Correcting suggestion that proton numbers are key to formation of ions, and fixing omission of mention of nuclear reaction and molecules are not simply matters of personal preference. I also object to your suggestion that I have not been using tak page --JimWae (talk) 22:03, 17 July 2008 (UTC)

It also adds information about how atoms can vary & does NOT suggest that proton removal forms ions --JimWae (talk) 21:48, 17 July 2008 (UTC)

Well thank you for bringing this issue to the talk page. The lead section has undergone many reviews and several re-writes, but improvement is always possible. However, I would much prefer that we first reach a consensus on whether large-scale changes are necessary. Note that the lead is intended to be a short summary of the main article. It is beneficial therefore to keep it brief, rather than extending it to cover every possible fact. It is also expected that the "prose is engaging, even brilliant, and of a professional standard". Certainly you could agree that this can be a challenging task.

As for suggesting that proton removal forms ions, well the text only states that an ion is formed when the number of protons differs from the number of electrons.—RJH (talk) 22:15, 17 July 2008 (UTC)

-- a vaugeness that can easily be fixed --JimWae (talk) 22:17, 17 July 2008 (UTC) Saying the number of protons determines the chemical element and the number of neutrons determines the isotope of that element is epistemologically backwards. We do not count the number of protons & neutrons to determine the element or the isotope. We have determined that atoms of the same element have the same number of protons AND determined they sometimes differ in the number of neutrons. --JimWae (talk) 22:17, 17 July 2008 (UTC)

I just want to point out that the following definition was good enough for IUPAC for its glossary of chemical terminology, also known as the Gold book: "Smallest particle still characterizing a chemical element. It consists of a nucleus of a positive charge (Z is the proton number and e the elementary charge) carrying almost all its mass (more than 99.9%) and Z electrons determining its size."[1] --Itub (talk) 22:30, 17 July 2008 (UTC)

Reply:

• An atom is classified according to its number of protons and neutrons: the number of protons determines the chemical element and the number of neutrons determines the isotope of that element.

versus

• Atoms of the same chemical element have the same number of protons; atoms of the same element that vary in the number of neutrons are called isotopes of that element.

To me the second sentence has lost the context of what it means to be an isotope; it is ambiguous. The statement implies the number of neutrons are varying, whereas they are not. A fixed number of neutrons for a given element corresponds to a particular isotope. The first sentence makes that clear.—RJH (talk) 22:39, 17 July 2008 (UTC)

• Atoms can lose or gain protons in nuclear reactions, thereby becoming a different element with a different atomic number. Nuclear reactions also involve a change in the number of neutrons.

Discussion of radioactivity in the lead should be consolidated. Placing this at the end of the first scatters the discussion across separate paragraphs. Thanks.—RJH (talk) 22:39, 17 July 2008 (UTC)

edit conflict--

1. For a group of scientists "characterizing" might be fine, but for the general public it needs to be "unpacked". This is a general public encyclopedia

   If this is a general issue with wikipedia, then it's probably off topic for this talk page. Wikipedia pages aren't written for a specific audience education level. (See photon for example.) Generally my impression has been that a page only needs to be internally consistent regarding education level, while striving to explain jargon particular to the speciality.—RJH (talk) 18:54, 18 July 2008 (UTC)

   Characterizing may sound like a scary word, but at least is not misleading like saying that an atom "has the chemical properties" of an element. Elements have many chemical properties that are not displayed by single atoms. If a simple verb is desired, one could say that "an atom is the smallest particle that can be said to be a chemical element". --Itub (talk) 07:17, 19 July 2008 (UTC)

2. If the article does not give at least some brief, detailed explanation of how atoms combine, it has not told the story of atoms. The only current explanaton is buried almost half-way down in the article as "By this mechanism, atoms are able to bond into molecules and other types of chemical compounds like ionic and covalent network crystals". This is assuming too much about what the general reader already knows on the topic.

   As molecules depend on the element involved, the consensus was to rely on the chemical element page for most of that information. For this reason, various details were pared back to just focus on the atom as an issolated entity. Yes, perhaps it may make sense to remove (or alter) the sentence you mention as well.—RJH (talk)

3. In general, I find scientific writing sometimes suffers from the delusion that the author is witnessing the "creation" of the universe & is involved in the "planning" of the next step. Thus we get terms like "building block" & phrases like "the number of protons determines the element" - rather than acknowleding that science is a discovery, not a building project. --JimWae (talk) 22:42, 17 July 2008 (UTC)

   I'll assume you're writing in good faith and not really trying to insult us here. It's important to keep in mind that this is an encyclopedia, not an article in a general public science magazine. We don't need to popularize science here; just present the facts in a transparent and readable manner.—RJH (talk)

   • I did not mean to be insulting, and did not mean it to single out anyone in particular - perhaps I should have called it a meme. I do not think you will find any of my edits were "popularizing" science --JimWae (talk) 23:28, 17 July 2008 (UTC)

4. OK, VARY might be ambiguous too. Instead of atoms of the same element that vary in the number of neutrons are called isotopes of that element we could say atoms of the same element which differ in the number of neutrons are called isotopes OR atoms with the same number of protons but a different number of neutrons are called isotopes.

   The last seems better, but I think it still doesn't quite capture the fact that atoms in an element with the same number of neutrons belong to the same isotope.—RJH (talk) 23:21, 17 July 2008 (UTC)

Proposed change to lead: discussion of radioactivity

Per the discussion with JimWae above, I think it makes sense to expand upon the following sentence in the lead:

In atoms with too many or too few neutrons relative to the number of protons, the nucleus is unstable and subject to radioactive decay.

JimWae's wording could be adopted by inserting the following text after the above sentence:

As a result, the nucleus can gain or lose or gain protons, thereby becoming a different element with a different atomic number. Nuclear reactions can also involve a change in the number of neutrons.

Does anybody object to this idea, or want to present some better wording? Thank you.—RJH (talk) 14:41, 23 July 2008 (UTC)

• "Too many or too few" suggests there is a "Goldilocks number" that is "just right". Many elements are unstable no matter how many neutrons they have --JimWae (talk) 18:26, 23 July 2008 (UTC)
  • True. The first sentence of the 'Radioactive decay' section would probably work better as a summary.—RJH (talk) 15:29, 24 July 2008 (UTC)

    Then again, it shouldn't be necessary to repeat information presented earlier in the lead. This may be sufficient:

    Each element has at least one isotope with unstable nuclei that can undergo radioactive decay. This can result in a transmutation that changes the number of protons or neutrons in a nucleus.

    Will this work?—RJH (talk) 14:54, 27 July 2008 (UTC)

g vs. kg

Why are the particles masses given in "g" instead of "kg" as in the International System of Units? I think that particles masses are given in kg in practically all textbooks. Eklipse (talk) 15:24, 24 July 2008 (UTC)

Good question. I'm not really sure why. They needed to be made consistent at some point and they ended up as grams. The CRC Handbook uses kg, so that would seem like the logical choice.—RJH (talk) 15:35, 24 July 2008 (UTC)

Kilograms should be used. Headbomb {ταλκ – WP Physics: PotW} 15:52, 24 July 2008 (UTC)

Done. Hope I didn't forget anything. Eklipse (talk) 19:58, 27 July 2008 (UTC)

The only one I wasn't too happy about was having to change the definition of atomic mass from grams to kg in the "Mass" section. Is that revision acceptible with everybody?—RJH (talk) 17:02, 2 August 2008 (UTC)

Template:Atomic models

I created this template so people could quickly-browse atomic models. The skeleton is there, but little meat. Help is appreciated. Headbomb {ταλκ – WP Physics: PotW} 01:29, 1 September 2008 (UTC)

I'd like to suggest using the {{navbox}} format instead. It can include the same information, but you only have to expand the table rather than each row.—RJH (talk) 17:06, 8 September 2008 (UTC)

How about looking at the picture of a real physical nuclear model, light in Talk:Nuclear model.WFPMWFPM (talk) 20:12, 8 September 2008 (UTC)

I changed it into a navbox and expanded things a bit. Headbomb {ταλκ – WP Physics: PotW} 22:10, 8 September 2008 (UTC)

Thank you.—RJH (talk) 14:55, 9 October 2008 (UTC)

"Physicists Create Millimeter-sized 'Bohr Atom'"

The article formerly in the "Size" section formerly included the text "The largest atoms observed, as defined by the distance of the outermost electron from the nucleus, have a diameter approaching one millimeter for several orbits of the outermost electron. " This was deleted 16:48 on 14 August by BenRG with the comment "The article says they manually put an electron in a large semiclassical orbit from which it almost immediately decayed." The extremes of physics are not something to delete and ignore. The article, in Science Daily, from July 1, 2008 [2] is titled "Physicists Create Millimeter-sized 'Bohr Atom'." It says they intentionally created a Bohr-like atom with an electron in a defined orbit, (not "manually" since their hands are large and electrons are small) but by adding energy to the outermost electron. It is still an atom even if the outermost electron is at an unusually high energy level. Many substances in nuclear physics are "artificially" created and last for very brief periods before changing or decaying. The article said "Using laser beams and electric fields, Rice physicists coaxed a point-like, "localized" electron to orbit far from the nucleus of a potassium atom." Scientists from Oak Ridge National Laboratory and Vienna University of Technology collaborated with a team from Rice University led by Barry Dunning, and it was published in Physical Review Letters. It is said to have applications "in next-generation computers and in the study of classical and quantum chaos." I feel that this demonstration should be included in the article, and welcome any suggestions for how to make it as clear as possible. An atom with a diameter of about a millimeter and a localized electron in a well defined orbit is atypical but worth noting. Edison (talk) 15:37, 5 September 2008 (UTC)

The abstract at Physical Review Letters can be seen at [3] for "Realization of Localized Bohr-Like Wave Packets," by J. J. Mestayer, B. Wyker, J. C. Lancaster, F. B. Dunning, C. O. Reinhold, S. Yoshida, and J. Burgdörfer, Phys. Rev. Lett. 100, 243004 (2008) . It says "Although these wave packets slowly dephase and eventually lose their localization, their motion can be monitored over several orbital periods. These wave packets represent the closest analog yet achieved to the original Bohr model of the hydrogen atom, i.e., an electron in a circular classical orbit around the nucleus. The possible extension of the approach to create “planetary atoms” in highly correlated stable multiply excited states is discussed." Edison (talk) 16:29, 5 September 2008 (UTC)

I've just taken a look at the paper itself, and it says that the radius of the orbits they created is circa 5 µm, not "approaching one millimeter" as the Science Daily article said. I assume this is a mistake by Science Daily or by whoever wrote the Rice University press release. Also, the paper makes it clear that the goal of the work is to create semiclassical orbits and not large-radius orbits as such. So I'm not sure this is actually the largest orbital radius ever achieved, since maximizing the radius wasn't their goal.

My edit summary also said that the sentence I deleted "seems more misleading than informative", and I still feel that way. Discussions of atomic radii normally refer to ground-state atoms and ions. Once you admit excited states, I think the only real limit to atomic size is what one considers reasonable to call an "atom". I could place a proton and an electron a centimeter apart in an evacuated chamber and declare them to be an excited state of hydrogen provided they eventually collapsed into ground-state hydrogen. But I'd be more likely to describe that as a proton and an electron merging into an atom or as an H⁺ ion capturing an electron. I guess I wouldn't object to something along the lines of "If excited states are considered there is no upper limit to the size of an atom in principle. Electrons have been placed into semiclassical orbits with a radius of 5 µm in the lab, over 10,000 times larger than a typical atomic radius.[cite paper]" -- BenRG (talk) 18:26, 5 September 2008 (UTC)

I thought that the Bohr orbits were supposed to be stable and not involve energy loss radiation. The energy loss radiation was supposed to occur "per saltum" as the orbit fell from one level to another. WFPMWFPM (talk) 16:57, 6 September 2008 (UTC)

The man made black hole?

Tomorrow they will do some experiments on the subatomic level, is that worth it, is that on the level, why waste money, what kind of black hole can be created or r they overdoing things big time? I dont thing force is great enough to produce such effects?! Who cares what happened in first second, i think there were many big bangs! —Preceding unsigned comment added by Ornamentalone (talk • contribs) 22:22, 9 September 2008 (UTC)

Atoms are not black holes nor are they relevant to the LHC. You are off topic. Eeekster (talk) 22:05, 16 September 2008 (UTC)

May be you should have more respect and learn how to read, i wrote on black hole experiments, subatomic level, as all matter must consist of atoms, i only concentrated on black hole experiment! —Preceding unsigned comment added by Ornamentalone (talk • contribs) 22:23, 16 September 2008 (UTC)

Not all matter consists of atoms. Protons (what will be used in the LHC) are matter and don't consist of atoms. Nor do black holes consist of atoms. Take this discussion to the LHC pages, not here. SBHarris 00:24, 17 September 2008 (UTC)

If you really want to discuss the possibilty of black holes from the LHC, the best place would be Safety of the Large Hadron Collider. Eeekster (talk) 00:34, 17 September 2008 (UTC)

WHAT AN ATOM IS.....in a 6th graders mind :)

An atom is everytihg in the world, air,liquid and,gas. —Preceding unsigned comment added by 70.179.87.249 (talk) 22:10, 8 October 2008 (UTC)

==That's the way kids think. We've got 5 different things, all similar, and it's an accomplishment that he came up with 5 different things. And so he is learning. So he has the right attitude and how can we help him with that? I once heard an interview on the radio with a kid who had taken an interest in the planets and knew more about them than I did (dubious criteria). I think that helping organize the information is important. I have memorized the periodic table and it has helped a lot. WFPMWFPM (talk) 22:06, 19 October 2008 (UTC)

Well, unfortunately, there is a space limit on these articles, so information on chemical element and state of matter ends up on other pages; otherwise the article would need to be as long as a book to cover everything. We do have articles on air, liquid and gas, so probably those would be good starting points for somebody seeking information. We also have a simple english article on the atom that could be expanded. Thanks.—RJH (talk) 15:28, 20 October 2008 (UTC)

==How about a simple article about the periodic table, and how it could be better understood if people didn't insist on making it so complicated, Asimov did it. WFPMWFPM (talk) 17:53, 20 October 2008 (UTC) But he's not a man of few words. WFPMWFPM (talk) 17:56, 20 October 2008 (UTC)

==Okay so there's a simple periodic table article. But it didn't recognize me as WFPM when I tried to log in and I made 2 contributions as ?. And I dont dare suggest how many complications are buried in the standard periodic table. WFPMWFPM (talk) 18:27, 20 October 2008 (UTC)

This disussion is moving away from improvements to this page, and so is off topic. You might mention your concerns on the talk pages of the articles in quesion.—RJH (talk) 22:03, 20 October 2008 (UTC)

== I'll try something and see what happens. And what's —? WFPMWFPM (talk) 03:12, 21 October 2008 (UTC)

Like charges repel

Like charges repel. What are the forces that keep the protons with similar charges are so close to each other in nucleus of an atom. The distance among electrons and protons are greater as compared to the distance among protons in nucleus.96.52.178.55 (talk) 16:46, 24 October 2008 (UTC) Khattak

Talk pages of articles are for suggesting improvement to the article, for other questions ask WP:Reference desk. BTW, see nuclear force. -- Army1987 (t — c) 16:57, 24 October 2008 (UTC)

Comment from an outsider

I have just now made some minor changes and have noticed other points that need expert attention. For example, there is a difference between electrons and orbitals that isn't obvious in places in this article. Also, the level of sophistication of the text varies quite a bit. Finally, chemists would argue about the article's first sentence since the stable macroscopic manifestations of many elements are not carried over to the atomic level. [Example: Elemental nitrogen is N₂, so an atom (N) of this element doesn't behave like a mole of nitrogen in the room where you are now reading this sentence.] I'm not a regular contributor to this long article, so take these comments for what they are worth. - Astrochemist (talk) 16:44, 25 October 2008 (UTC)

Thank you. Yes the page has undergone some revisions since it became FA, and it might need some editing for use by a general-audience. Some of the contributors may assume too much knowledge on the part of the typical reader, for example. I also see your point about the first sentence. It has been rehashed several times, and it looks like it still isn't satisfactory. That definitely needs to be debated some more in order to get it just right.—RJH (talk) 17:11, 25 October 2008 (UTC)

Definition of atom

Here are some of the definitions I found on the net:

• The smallest particle of an element which can enter into a chemical combination.

Half baked definition. The "smallest" particle of an element would be electrons/protons/neutrons since elements are made of them. I get what they are trying to argue, but the wording is very poor.

• The smallest particle of matter that can exist in combination with other atoms, building up or constituting molecules.

Better definition, but not quite there.Relies on the concept of matter, which is often (though not always) ill-defined. It is also a circular definition.

• An atom is the smallest unit of chemical structure, and no chemical change can alter it.

Flat out wrong, as you can ionize or exite atoms and that is certainly a change.

• An atom is the smallest irreducible constituent of a chemical system.

Best "layman definition", but not one that is true. Atoms can be reduced to electrons, proton and neutrons, the later two can be broken into up and down quarks.

• The smallest unit into which matter can be divided without the release of charged particles. (Encyc. Brit.)

Horribly worded and the fact that atoms regularly undergo beta decay means this definition is not true.

• The smallest particle of an element that can not be broken down without losing its properties.

Other definitions define the atom in terms of the element. However, the element is in turn defined in terms of the atom, which seems to result in a circular definition.

Ions because problematic under this definition, as removing an electron changes the properties of that element (say Iron), even thought it remains the same element (Iron, albeit charged).

Examples:

• An atom is the smallest particle differentiable as a certain chemical element.
• The smallest unit of a chemical element that can exist.
• The atom is the smallest particle that constitutes a chemical element.

Here is the current definition:

• The atom is the smallest unit of an element that retains the chemical properties of that element.

Here is my first attempt at a definition to address Astrochemist's concern:

• The atom is the smallest component of matter that can not be further broken down by chemical means, and it forms the basic unit of a chemical element.

although I'm not sure if that would include the hydrogen ion. Does anybody have a better definition?—RJH (talk) 20:56, 27 October 2008 (UTC)

The real definition an atom is "any bound state of protons and electrons", with a possible extension to include ionized hydrogen. You can generalize it to any bound state of baryons and leptons (exotic atoms are those not made of protons/electrons). This is a rather complicated definition for the reader. Simply saying an atom is a pack of bunched up protons/neutrons(optional)/electrons would be both technically accurate and accessible. Headbomb {ταλκ – WP Physics: PotW} 04:34, 29 October 2008 (UTC)

A possible problem with your first definition is that it could also be used to describe H₂. Perhaps something like: "An atom consists of a central nucleus with one or more closely associated electrons..." &c.—RJH (talk) 17:41, 29 October 2008 (UTC)

Yes that would be satisfactory. Then the concept of molecules could be introduced as a pack of bunched atoms.Headbomb {ταλκ – WP Physics: PotW} 18:15, 29 October 2008 (UTC)

Okay I reworked the lead paragraph it a little:

An atom is a basic unit of matter consisting of a central nucleus surrounded by a cloud of negatively charged electrons. The dense nucleus contains positively charged protons and electrically neutral neutrons. The electrons in an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain held together by the electromagnetic force, forming a molecule. When the number of protons in the nucleus equals the number of electrons, the atom is electrically neutral; otherwise it is an ion and has a net positive or negative charge. An atom is classified according to its number of protons and neutrons: the number of protons determines the chemical element and the number of neutrons determines the isotope of that element.

Does anybody see any further issues with this? Thanks.—RJH (talk) 18:49, 29 October 2008 (UTC)

I would write "often contains electrically neutral neutrons" as neutrons are not a requirement (or at least something to that effect). I have minor reservations about "basic unit of matter", but to correct that would make the lead waaaaaaaaaay too technical (matter = stuff made of elementary fermions, to the basic units of matter are quarks and leptons, rather than atoms). Wikilinking matter would be sufficient IMO.

Understood. The "basic unit of matter" statement was meant in terms of chemistry rather than physics, which is why I didn't put "fundamental unit". I was tempted to say "basic component", but that seemed unnecessary.—RJH (talk) 17:19, 30 October 2008 (UTC)

How about

An atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains positively charged protons and often, but not always, electrically neutral neutrons. The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral, otherwise it has a positive or negative charge and is an ion.

An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determine the isotope of the element.

Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:45, 29 October 2008 (UTC)

Given that no nucleus contains several protons but no neutrons, I'd rather say "The atomic nucleus contains positively charged protons and electrically neutral neutrons (except for the hydrogen-1 nucleus, which is a single proton)." Except for this minor point, your proposal sounds OK to me. -- Army1987 (t — c) 10:24, 30 October 2008 (UTC)

Well, unfortunately, when you go there you also have to correct for the plural form of protons. My preference is to go with the least distracting form and then clarify it in the body of the article. How about, "The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons." I.e. leave it vague, as it is covered by the end of the paragraph. We could add a sentence at the end saying that hydrogen-1 is the only nucleus with no neutrons.

I'm not real fond of the paragraph break; the article needs to follow Wikipedia:LEAD to avoid FAR, so I think it should be kept to four paragraphs.—RJH (talk) 17:19, 30 October 2008 (UTC)

Well since we're describing what a nucleus is rather than defining it, sure, as long as hydrogen-1 is mentionned as the only stable atom/isotope without neutrons. Remove the paragraph break if you want. So something like

An atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons (except in the case of Hydrogen-1, which is the only stable isotope with zero neutrons). The electrons of an atom are bound to the nucleus by the electromagnetic force. Likewise, a group of atoms can remain bound to each other, forming a molecule. An atom containing an equal number of protons and electrons is electrically neutral, otherwise it has a positive or negative charge and is an ion. An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determine the isotope of the element.

Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:47, 30 October 2008 (UTC)

More or less, although I still think the hydrogen-1 exception disrupts the flow. Perhaps we could make it a footnote instead? Otherwise, I think it would be better to do away with the parentheses, based on past experience with FAC issues.—RJH (talk) 20:05, 30 October 2008 (UTC)

Rare Forms

"For unknown reasons, antimatter particles are rare in the universe, hence, no antimatter atoms have been discovered in nature.[130][131]"

I would suggest re-wording this sentence (or removing it entirely?). The main reason for the rarity of antimatter particles in nature is their instant annihilation when they come into contact with matter. There are two referenced articles after the sentence that say this. 86.131.69.5 (talk) 22:45, 28 November 2008 (UTC)

Unfortunately, using the same logic I can say that matter particles are relatively rare in the universe because 99% were wiped out by antimatter. The sentence is a reference to baryogenesis, which remains incompletely explained and is therefore unknown. Perhaps it can be re-worded into a more satisfactory form?—RJH (talk) 22:59, 28 November 2008 (UTC)

However theoretical I can't accept that the reason for the rarity of antimatter is unknown. How about re-wording it as follows, or similar? "No naturally occuring antimatter particles have been discovered as each annihilates when it comes into contact with its corresponding particle.[130][131] The baryogenesis theories offer incomplete explanations." It maintains the theoretical aspects, gives a reason for antimatters rarity and provides the reader with links to related topics. Any ideas? Kae1is (talk) 17:41, 29 November 2008 (UTC)

That works for me.—RJH (talk) 19:16, 29 November 2008 (UTC)

That's a hypothesis and we shouldn't declare things to be settled just because the idea makes sense. The reason for the matter-antimatter asymmetry is unknown, or at the very least, not firmly established. If you can't accept that, then you have a problem with the state of science in general, because there's a lot we don't know.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:41, 29 November 2008 (UTC)

My understanding is that there are several competing theories regarding baryogenesis, and so the matter remains unresolved. Whether you say it is incomplete or unknown seems to be equivalent in this case. Do you have some alternative wording to suggest?—RJH (talk) 20:03, 29 November 2008 (UTC)

I would simply mention that relative to matter, antimatter particles a relatively rare, and that the reason for this rarity is "not yet fully understood" and point to the baryogenesis article. I don't have a specific wording to propose however.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 20:44, 29 November 2008 (UTC)

The initial reason for the rarity is not fully understood, but the current reason, annihilation, is fairly self evident, which was my query in the first place. There was no distinction made. How about:

"No naturally occuring antimatter particles have been discovered as each annihilates when it comes into contact with its corresponding particle.[130][131] The first causes of this rarity is not yet fully understood, however, the baryogenesis theories may offer an explanation." Kae1is (talk) 14:17, 30 November 2008 (UTC)

In retrospect your statement is not correct: naturally occuring antimatter particles are created continually from radioactive decay. Also see proton-proton chain reaction, which relies on the production of positrons.—RJH (talk) 19:47, 30 November 2008 (UTC)

In that case the current sentence is also incorrect and should be changed. If it's worded, "Naturally occuring antimatter particles are rare as each..." 86.131.69.5 (talk) 21:21, 30 November 2008 (UTC)

de-indent: No, the current statement is correct. It asserts scarcity, rather than lack of existence.—RJH (talk) 19:54, 1 December 2008 (UTC)

atoms and molecules

Atoms are the basics of life. Everything we know is made of atoms. Do you know what an atom is? I don't. I do you know what a molecule is? It is a bunch of atoms put together just like our bodies. —Preceding unsigned comment added by Hayden014 (talk • contribs) 13:55, 18 December 2008 (UTC)

Didn't they warn you to stay away from the purple mushroom? ;-) —RJH (talk) 19:30, 18 December 2008 (UTC)

See also

a link to Intel Atom requested. —Preceding unsigned comment added by 71.206.65.120 (talk) 00:34, 17 January 2009 (UTC)

It's on Atom (disambiguation). Vsmith (talk) 19:08, 20 January 2009 (UTC)

Alternative Atom Model

To date, although the theories on atom model are said quite established, there are still few unsolved questionable problems, such as the non-linearity in Moseley X-ray plot for higher atomic mass number, the 'V' shape of H2O molecule, the revolution of electrons in atom and etcetera. An alternative atom model is proposed for alternative understanding. More detail explanation is presented in an alternative atom model Kongkokhaw (talk) 16:30, 20 January 2009 (UTC)

Has this been published in a peer reviewed journal? If not, see WP:FRINGE. Vsmith (talk) 19:04, 20 January 2009 (UTC)

Spaces Between Atoms

If everything is made of matter, of which the building blocks are atoms, of which the building blocks are fermions (quarks and leptons) and gauge bosons and maybe Faddeev-Popov ghosts, of which the building blocks are what? ( Strings?). Still, we do not tackle what is in-between the fundamental particles? How is "empty space" accounted for? Are we currently just defining this into being (or some kind of non-being) and not talking about it? andersole (talk) 00:10, 21 January 2009 (UTC)

If you think about matter as waves (per the wave-particle duality), then it is not clear there actually is empty space between particles. An interesting book that tackles this question is Nothingness, The Science of Empty Space by Henning Genz (2001). See also the vacuum state, virtual particles and vacuum energy articles. But yes there does seem to be a level below which the fundamental nature of space remain unclear. I've seen some articles that talk about "atoms of space" for example.—RJH (talk) 23:05, 21 January 2009 (UTC)

Atoms

Element consists of atoms and atom consists of protons, neutrons, electrons depend upon the element. What are their masses made up of? Means what kind of material (matter) is in their masses? 96.52.178.55 (talk) 02:33, 5 March 2009 (UTC) Khattak