Talk:Atom

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Finish sections:

  • Atoms in the universe and our world: discuss the appearance (and formation?) of atoms after the big bang; how many atoms in universe; spatial distribution of atoms
    • Atoms in industry: role of individual atoms in chemistry, nuclear fusion, fission
    • Atoms in science: how individual atoms are identified (spectroscopy) and investigated (X-ray crystallography)
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Contents

[edit] Atomic orbital wavefunctions illustration

The illustration of the atomic orbital wavefunction is lovely to look at, and I get a real sense that I am seeing something important... except I have no idea what it is. Am I looking at a photgraph of an atom? I suspect not. Are the dark areas nothing and the lighter areas something? Probably. Am I looking at a theoretical model or an image generated by some clever device which can observe the heart of a single atom? Or have I got that all wrong and maybe I should think of the illustration as some form of graph showing the theoretical increase and decrease in some quantity over the two dimentional plane? Are the images slices through something which has a three dimentional existence? I assume so, but how does the slice shown relate to the rest?

Also, what about spin. I see a glowing gradation in different parts of the image. Am I supposed to imagine that those hazy hints at substance also somehow spin? Is that a real three dimentional spin as with a roundabout, or some notional spin which has a different meaning than the one which Mr and Mrs Average might understand?

When an electron 'leaps' from one shell to another, does it drift from one of those hazy glowing areas to another, or does it snap from the one to the other in an instant, or have I got the whole thing wrong.

Should I imagine those glowing areas, spinning while at the same time orbiting the core? Is that how spin, azimuthal quantum numbers and orbital angular momentum relate to each other?

It is tempting to say, "I am pretty intelligent yet I don't understand this stuff, so your explanation must be wrong" but I am willing to accept my share of dimness here if somone with better understanding can shed some light on this area.

I would much appreciate it!

Sign your comments, please. Too many questions to answer all at once. For atomic orbitals, you're looking at basically a 3-D graph of a math function, which outputs probability density of an electron being in a certain volume, and you're seeing this probability as brightness (color is for show). The math functions have been generated as solutions to the Schroedinger equation for hydrogen. Each function is something like a picture of where a pair of electrons is most likely to be in space, in an atom. Each of those areas (orbitals) is either one or two electrons, all smeared out. When electrons go from one to region another, they don't do so in an instant. They're moving at some good fraction of the speed of light which varies from something on the order of 1/130th to 2/3rds or so (the inner electron of a uranium atom is bound at 132 kev which is something like 30% of its rest mass, which works out to around .63 c). So that's the speed with which electrons "hop" from one of these regions to another. But once in a region, an electron is everywhere at once there, in that funny quantum way. No, these things don't spin as they orbit the core. The orbital spin is already taken care of, in their lobed shapes. Which turn into ring-like donuts at very, very high spin. For lower spin, you're just seeing some kind of odd wave-like hybrid of a donut and the fuzzy globular ball that means no spin. SBHarris 05:39, 8 November 2006 (UTC)

[edit] First paragraph: meaning of "atom"

From Wiktionary:

  • Etymology of tomography: Greek tomos (slice) + graphia (describing)
  • Etymology of atom: From Old (and modern) French atome, from Latin atomus ‘smallest particle’, from Greek ἄτομος, noun use of an adjective ‘indivisible’, from α- ‘without’ + τέμνειν ‘to cut’.

From Encarta:

  • [16th century. < Latin atomus < Greek atomos "unable to be cut" < temnein "to cut"]

I teach quantum mechanics, I have published numerous papers on its interpretation in peer-reviewed academic journals, and IMHO one of the most important implications of quantum mechanics is that dividing a material object is no longer the same as cutting it, which was taken for granted ever since people began thinking about the divisibility of matter. I don't quite understand why my edit of the first paragraph was undone. Since no reason was given, I restored it. How do others feel about it? If I am given a good reason for rejecting my edit, so be it.

Note: I have to do further work on the cookie cutter paradigm, to which article I have included a link here. Please check it out after a day or so. --Ujm 03:32, 17 October 2006 (UTC)

[edit] Mendeleyev?

Why is Mendeleyev not mentioned in the article? Surely he did a great deal in uncovering the structure of atoms. —The preceding unsigned comment was added by 212.238.247.196 (talk) 00:11, 7 December 2006 (UTC).

Yeah, and why doesn't it mention that when Democritus created the theory, it got turned down because Aristotle proposed another theory? Yctaabpjic 08:24, 18 January 2007 (UTC)Yctaabpjic Jan.18/2007

This article contains just a very short overview of the history; for more details, you should go to atomic theory. However, that one doensn't mention Mendeleev or Aristotle (or Gassendi, Descartes, Pauli, Fermi, and many others which contributed in one way or another) either. Maybe one day I'll add some of these people if I have time... Itub 12:34, 18 January 2007 (UTC)

[edit] Proton, Neutron, and Electron Quantities

I would like to see a basic explanation of the methodology used to determine the number of protons and neutrons in a particular atomic nucleus, and the same for the number of electrons that are said to be associated with it. From what are those numbers derived? Take any element in the periodic table. A particular element is said to have so many protons, and so many neutrons in the nucleus. How was that information discovered and when? A particular element is said to have so many electrons. How was that information discovered and when? 71.109.126.112 04:38, 13 January 2007 (UTC)Seeker

The closest answer to who and when for protons is Henry Moseley in 1914. He's the guy who discovered that atomic number is very nearly the same as nuclear charge, which means the number of the element in the periodic table is the number of protons in the nucleus. Rutherford had previously found charge on the nucleus was roughly half atomic weight. And also the number then of electrons in the outer atom, since they have to be equal. See the wikis on Rutherford model, Rutherford scattering and Bohr model for more. As for numbers of neutrons, that had to wait for discovery of the neutron in 1932 by Chadwick. After that, the composition of the individual nuclides was obvious from application of mass spectroscopy of their isotope masses. But a lot of people were involved in the work. SBHarris 04:55, 13 January 2007 (UTC)

Thank you for responding to my question. Could you please clarify your reference to mass spectroscopy? When I looked at the linked article I found that it appears that mass spectrosophy requires prior knowledge of atomic weight/composition. For example, "Different compounds have different atomic masses, and this fact is used in a mass spectrometer to determine what chemicals are present in a sample." It sounds like you need a set of prior facts about the content of the nucleus if you are going to make anything out of this mass spectroscopy. In this regard, it does not seem like this would be part of the answer. Please clarify. 71.109.126.112 02:36, 15 January 2007 (UTC)Seeker

The statement you refer to really only applies to molecular mass spectroscopy. In mass spectroscopy of single atoms as ions, the deflections are fully specified in terms of the well-known physics of the behavior of mass and charge moving at some velocity in a magnetic field, so that the mass/charge ratio of individual atoms can be directly calculated. If the charge on them is known (or is assumed to be one unit) then this allows direct calculation of isotope masses. For example, in 1920 it was observed (by JJ Thomson, as I recall, though he didn't initially realize what he was seeing) that there were two kinds of neon atoms, and they differed in mass by about two atomic mass units (i.e., by about the mass of two protons, as neutrons were not then known). SBHarris 03:42, 24 February 2007 (UTC)

[edit] ~1080 atoms in the universe?

Ummm...any proof of that? —The preceding unsigned comment was added by 89.252.226.19 (talk • contribs) 14:21, 14 January 2007.

Proof? Well, I was counting - but now you've distracted me so I'll have to start over...
Or, did you mean, is there a reference to support that estimate? Probably, but I don't know where. Got rid of all those zeroes - were there eighty of them? Did you really count them? Cheers, Vsmith 14:58, 14 January 2007 (UTC)
OK - I asked Google. See: http://www.madsci.org/posts/archives/oct98/905633072.As.r.html - the madsci supports the wiki number - and http://answers.google.com/answers/threadview?id=352789 - Seems there are less than a googol of them. Onward into the unknown... Vsmith 15:14, 14 January 2007 (UTC)

[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)

[edit] Patents .. put in after lock out is lifted

172.144.93.87 21:56, 17 February 2007 (UTC)

[edit] mergto proposal Atomos

this is the Greek origin of the word atom, already explained in atom V8rik 21:16, 23 February 2007 (UTC)


well i have a question about atoms. since there is alot of space between the center and the electrons, then whats inbetween? it can be air because air is made of atoms so whats inbetween there? sry that i put the question here, its just i could think of any other way to put it in other then this way.

[edit] Large number names

In the reference section, there is a quote: "There are 2,000,000,000,000,000,000,000 (that's 2,000 billion billion) atoms of oxygen in one drop of water—and twice as many atoms of hydrogen." The proper way to read that number would be 2 sextillion, not 2 billion billion. See Names of large numbers for reference.

Of course, in the real world, we call that number 2 × 1021. --Itub 09:48, 12 March 2007 (UTC)

[edit] Missing images?

There are a lot of missing images. It appears they should be there as what looks like code is present for them. A picture says a thousand words. 71.224.244.205 20:37, 16 March 2007 (UTC)Bryn.

[edit] Can an atom be charged?

Is a Na+-ion atom? —The preceding unsigned comment was added by 80.186.187.254 (talk) 18:30, 20 March 2007 (UTC).

I think that in most usages, charged and neutral atoms are both permitted, ie, ions are regarded as a species of atoms (charged ones). See the wiki on section on exotic atoms for even odder ones. —The preceding unsigned comment was added by Sbharris (talk • contribs) 20:04, 20 March 2007 (UTC).

Thanks for answering. Thats what I think too. But in Finland we teach in secondary school that atoms have as many protons as electrons. And I would like to check this thing and be sure. IUPACs golden book definition: http://goldbook.iupac.org/A00493.html There is nothing about the numbers of protons and electrons.

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