Talk:Atom

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[edit] Picture of an atom

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)

[edit] 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)


[edit] 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 on 2008-02-15.
1080 Champion, Matthew (September 11, 1998). How many atoms make up the universe?. MadSci Network. Retrieved on 2007-01-02.
1081 deGrasse Tyson, Neil (1994). Universe Down to Earth. Columbia University Press, p. 10. ISBN 023107560X. 

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)

[edit] 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] 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)

[edit] 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))

[edit] 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)

[edit] 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)