Talk:Atom

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I'm not sure a general rule regarding "less valence electrons means more reactive" is applicable. Fluorine and the other halogens are highly reactive, and they all have only 1 atom missing from their valence shell. Ed Sanville

uncut or uncuttable (indivisible)?

a means not and tomos means cutting. atom is typically translated with indivisible. I'll change it. AxelBoldt

I removed "even smaller particles which appear in nuclear reactions. The smaller particles (electrons, protons and neutrons) can be observed in many non-nuclear reactions; electrons are flying at your computer monitor and protons are swimming around in water and determine the PH. AxelBoldt

I'm picking nits here, but the proton example is not very good. While it is convenient to think of H⁺(aq) as a free proton that "swims" through the water, in reality it just isn't so. The proton is actually always surrounded by a coordination sphere of water molecules, with which it shares electrons (and is essentially covalently bonded). Sometimes this is represented as the formation of a hydronium ion (H₃O⁺), but even this is a simplification. In reality the extra proton is constantly interacting with multiple surrounding water molecules (and is likely exhanging places with hydrogen atoms in those molecules). Matt Stoker

I love etymology but I'm not sure that all encyclopedia users share my enthusiasm. Wouldn't it be better to relegate it to a sub-heading at the end? Unless, of course, the etymology actually has some bearing on the topic. What do the panel think? -- Heron

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How large is the estimated number of atoms in the universe?

Well, according to this definition (http://www.googol.com) of the term "googol", the number of particles in the Universe is estimated to be between 10^120 and 10^130. Since an atom is made up of particles, that means the number of "atoms" in the universe is considerably smaller than that. Under a googol, perhaps?

Currently, the best information we have suggests that the universe, and the number of particles within it, is infinite. The links above probably talk about the observable universe, which consists of those parts of the universe which are close enough so that the light emitted by them has already reached us. AxelBoldt 23:45 Oct 12, 2002 (UTC)

If I remember correctly there are/were some theories saying that the universe is finite, although very large. I would be interested in knowing more about this. Who thinks what why? Any pointers?

It is, of course, possible that the universe is infinite in size but finite in number of particles. anthony (see warning) 00:40, 20 Aug 2004 (UTC)

I have not recent data at hands, but the total mass of the universe is a very often cited data (it is also very questioned becouse is very difficult to extimate and its value has impact in the way the universe is exmpandig and evolving).

In the view this is only an extimation I will use the value I have found at Orders of magnitude (mass) 3 × 10⁵² kg as the total mass of universe.

I will suppose that the universe is made only of Hydrogen (this is not true,I konw, but it is a rasonable approximation for this calculus). Since in 1 g of Hydrogen there is 6.022 × 10²³

Number of aoms in the universe ≈ 3 × 10⁵² kg × 1000 g/kg × 6.022 × 10²³ atoms/g = 1.8 × 10⁷⁹.

Please take care that this is only an extimation of magnitude! Do not take this as an exact number!! AnyFile 19:31, 26 Oct 2004 (UTC)

That's within the range I had added to the article, 4.0e78 and 6.0e79. Good to hear it from another source. Thanks. --Whosyourjudas (talk) 23:55, 26 Oct 2004 (UTC)

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Someone asked, in the following comment that I removed from the article:

(what was the name of the model Aristotle used? where atoms where like small pebble with different shapes)

I think the questioner was thinking of Democritus, the atomist, and not Aristotle, who denied atomism. Democritus believed that the properties of atoms were determined by their shapes. I put in a link to Democritus, but I think Democritus' idea should be discussed in this article. --Heron

Actually in his works Democritus does not concern very much on the phisical aspect, but the fellows of his theory (amoung with Epicurus and his fellows Epicureans, the latin Lucretius and other greek and latin atomistic or epicureans) does concern of it.

The problem, in my opinion, is that written as it is know, the sentence concern more to the Etymology sections. The Historic section is terrible small and only a list of link. But if you really want to written an historic section you have to consider also the philosophers contributions.

Before the science born as a separate discipline (and also later) philosofers do dealt whith argoment we now consider science.

After I have said this, that is of general consideration, in this particular case it should take in consideration that the atomic therory of ancient has only few connection with the modern one (the most important one is by no doubt the name atom). The ancient concept of atom is very different to the modern one both in physical and ideological aspect.

For that reason the ancient history could be short, but it shoulud be expanded. (Of course the modern history need be expanded even more.)

Consider that this article could be read by persons interested in this part of history (e.g. students of phylosophy at high scools). So a part on this should be insert. May be it could be a completely separated section (or sub section). May be it could be only a brief explanation that mention link, but not just a list of link, a complete explanation, even if brief.

I will try to contribute to this, but my high-school study are a little be distant in time. This part of phylosophy are a little be neglect in study becouse it is not consider important. This is not proble of today, but also in the ancient time the book of atomistic, epicureans and other considered minor schools have benne neglected in favour of more famouse philosopher (Aristotle, Platone). As a conseguence we noe have very little written matirial of them and very little study on them. AnyFile 19:39, 26 Oct 2004 (UTC)

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

Come now, titans of chemistry! Surely, we can come up with a more concrete and more interesting introduction than saying an atom is part of a system. ("What system?")

Can we instead say that atoms are what you get when you take a blob of matter and break all chemical bonds in that blob, and then at that point each particle is an atom, it is a pure element, has an atomic number, might be able to form ionic or covalent chemical bonds with certain other atoms to form molecules, etc.?

So what's stopping you? Hop to it :-). -- Cyan

Contents

1 Need a better image 2 problem with proposed structure 3 atomic mass - mass number 4 Link suggestions 5 Coverage of "Element" 6 Also see 7 Atoms and ions

Need a better image

We really need a better image of an atom. The bohr model is ancient and inaccurate. In any case, I removed the caption "The electrons move rapidly around the nucleus." because that's just not true. Electrons exist as a standing wave which is "smeared out" throughout the orbital. The electron occupies all positions in the orbital at the same time. anthony (see warning) 00:38, 20 Aug 2004 (UTC)

The image of Bohr model is what, in my opinion, most people figure out what an a tom is. I do not know what a better image could be. Consider that in most simple explanation the Bohr rappresentation (I deliberately written rappresentation ins tead of model) could be enough. It could be enouth for simple exmplanation of a lots of simlple phisical and che mical phenomenon (in many of them it is enough to condider the whole atom as a s phere or as a disk of unspecified shape).

This of course is not a rappresentation of what modern physics consider an atom, but I really do not how an easy comprensible image could be. We can insert an image of orbital (a rapresentation of the probibility where an electron could be found in space around the nucleus), but it would be difficult to understen, it woul be the rappresentation of the electron around (or better speaking 'in the') atom, not of all the atom and there are lot of proble ms I can no cite here for brevity (for example the probability is a sum of a lot s of orbital).

In my opion it could be valuable an image of the atomical disposition in matter structure structure (the way the atoms dispone them in space). This image is of more interst of structural physics, cristallography, stereo-chemistry and other specific sectors, bur it could b e interesting here also (If matter is made of atom, how atoms made matter?) AnyFile 19:44, 26 Oct 2004 (UTC)

I went ahead and updated the Atom Image to show a probability cloud instead of a circular Bohr orbit. I know this is controversial and if people don't like the new image, I will put back the old one. Comments? ((PS: I also added a section discussing atom sizes)) FrankH 07:44, 13 Feb 2005 (UTC)

problem with proposed structure

the proposed structure for Atom (see the todo list at the top of this page) states that the first section should discuss isotopes, ions, valence, size, half-period, etc. without discussing theory. however, all of these are based in atomic structure, whcih is entirely theory (and is to be discussed in the theory section). I'm wondering if the structure should be re-written to integrate these sections into an overall atomic theory section that discusses properties and their theory-based causes. the article is already somewhat structured like that, and i've been working to clean up and clarify the current content. the wikiproject science guidelines don't seem to fit this article's content well. --Whosyourjudas (talk) 00:47, 11 Oct 2004 (UTC)

I agree the intro needs to include the theory behind all of it in abbreviated form and then expanded in the theory section. You have been doing a lot of work here. I've made some minor edits - will be back. -Vsmith 01:24, 18 Oct 2004 (UTC)

I needed a project - this seemed like fun :) Whosyourjudas (talk) 03:00, 18 Oct 2004 (UTC)

OK - modified proposed structure in to do list, needs more. Comments? -Vsmith 01:37, 18 Oct 2004 (UTC)

i did more modification to the to-do list - more in line with current article structure, but might still need work - article definitely does. Whosyourjudas (talk) 03:00, 18 Oct 2004 (UTC)

In my opinion information of what isotopes are, what are the size of atom and so on should be given, in a short form, at the beginning in the genral discussion. A reader should have a brief description of this in the general (and easy) sect ion without having the need to go in depth into more difficult section. As you say that there are different atoms whith different proton number, and th ey give raise to different element, you can shortly state that there are atoms w hith different number of neutrons and hence the isotope. The reason we are familiar to different element but not to different isotope is that in the grat part of our work we have to take into acccount difference betw een element (netween substance indeed) but we can ignore the isotope type unless we deal with nuclear problems.

Half-period: the radioactive aspect relate more to nucleus than atom. If you wan t to speak of half-period you could not give only the element type you have to g ive also the atomic number. The half-life are different from one isotope to othe r. In my opinion it is better only to give a link to another article (maybe radi active).

Studs of science! I've got a mind-blowingly basic question that must have a simple answer, though I've been quite unable to find a direct answer anywhere. Please set clear my cloudy head. So electrons are negative, right? And an atom's nucleus--thanks to those rather amicable protons--carries a positive charge, right? Why is it that everywhere else in science negatives and positives want nothing more than to get together like some microscopic gatekeeper and keymaster, yet when we turn to electrons and protons, the opposites are all about playing coy with each other? What gives?

A simplistic explanation is a satellite orbiting around a planet. The gravitational force attracts the satellite toward the planet, and there is no repulsive force acting in the opposite direct. (This is analagous to hydrogen with one electron.) The satellite's forward velocity is what keeps the satellite moving in an elliptical orbit rather than just plummeting toward the planet. Note: this explanation is not consistent with the quantum model! — Brim 19:49, Feb 11, 2005 (UTC)

atomic mass - mass number

The atomic mass or nucleon number of an element is the total number of protons and neutrons in an atom of that element, - this is ambiguous and incorrect. The mass number or perhaps atomic mass number refers to the number of nucleons in a nucleus. The atomic mass refers to the actual mass of the isotope or to the average mass of all the isotopes. Atomic mass is equal to mass number only for C-12 by definition. Binding energy effects make the atomic mass for all other isotopes differ from their mass numbers. The atomic mass is used extensively in stoichiometric calculations as the atomic mass in grams of a mole of the substance. Mass number or nucleon number are distinct from atomic mass and useless in stoichiometric work. This needs to be rigerously applied to avoid confusion. -Vsmith 16:30, 2 Nov 2004 (UTC)

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This may appear quite trivial, but I'm intrigued by the statement that ninety one elements occur naturally on earth. The generally accepted value is 92 (by search on Google at least), which is easy to understand (from a naive point of view) as a consequence of Uranium (92) being the element with the highest atomic number of the commonly occurring elements. But several elements (Technitium, Promethium, Actinium come to mind) are very rare in nature, and occur (almost) exclusively as decay products, so could arguably be excluded from the count. And to be fair, other elements (neptunium, plutonium) undoubtedly do also occur naturally via similar processes. So how do we arrive at the consensus of 92 (or 91 as used in the article)? If all elements were listed in order of abundance, is there a natural cut-off point at which we could decide the correct number to use? Sorry to be such a pedant, but I think that that some justification is needed here.

Looking at the article on Periodic Table, possibly a link to (and expansion of) Primordial Elements might be appropriate. And further, to be consistent with the Periodic Table article, the value should actually be 83 naturally occuring elements (excluding synthetic and decay elements (the distinction actually is broken in the article)).

-Kram 21:43, 12 Dec 2004 (UTC)

Link suggestions

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Tip: Some people find it helpful if these suggestions are shown on this talk page, rather than on another page. To do this, just add {{User:LinkBot/suggestions/Atom}} to this page. — LinkBot 10:37, 17 Dec 2004 (UTC)

Coverage of "Element"

Is there too much information on elements in the article (being redundant with element)? This is an encyclopedia not a treatise/textbook (see WikiBooks) Dpr 03:36, 10 Mar 2005 (UTC)

Also see

Could we also consider added a 'Also see' page. Because Atom also happens to be the name of a popular content syndication format similiar to RSS. --Mayuresh Kadu (India) 04:02, 20 Apr 2005 (UTC)

Atoms and ions

This sentence reads a little oddly:

"Every atom has a number of electrons equal to its number of protons; if there is an imbalance, the atom is called an ion."

The first part seems to say that an ion is not an atom, the second part that an ion is a type of atom. --Edcolins 21:30, May 13, 2005 (UTC)