Talk:Molecule

The definition of a molecule as "the smallest indivisible portion of a substance that retains chemical and physical properties" is widespread among encyclopaedias and vocabularies. However,it looks *very puzzling* to me. Most chemical and physical properties of a substance have sense only when we talk of a *set* of molecules together. For example,I see as plain nonsense asking something like "at what temperature/pressure will that single isolated water molecule boil/ice/melt?". I think no one will deny phase transitions of a substance are among the most basic physico-chemical properties of a substance,but at what number of molecules does this make sense?

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Isn't the "word analogy" thingy a little too puerile? I mean, if I follow the paragraph and add carbon atoms (carbon black in a first approximation) to water molecules (tap water in another approximation)... Isn't there any other analogy -- if necessary at all?--Unconcerned 10:08, 19 May 2004 (UTC)

Moved the analogy paragraph on the talk page. Besides, (CH₂O)₃ is not a sugar molecule but rather the chemical formula of a sugar. The analogy might work for chemical formula.--Unconcerned 01:15, 20 May 2004 (UTC)

Molecules are analogous to words. If one adds the letter "e" to the word "can", one obtains "cane". In a similar fashion, if one adds C atoms to H₂O (the water molecule), one obtains (CH₂O)₃ (a sugar molecule).

Contents

1 Question 2 macromolecules 3 Intro Paragraph 4 DNA Example 5 To Do / Wish List

Question

Do any Atoms and Molecules(?) stick to each other WITHOUT heating above 200 degrees F.

ANWSER: YES NO

THERE ARE: FEW MANY

Were(?) can I find the details.

How do you break ELECTRON BONDS, just methods used (passing one molecule over another (at room temp, while heating them))? I do not need to know the exact proccess.

thanks - Anonymous

Certain atoms and molecules (technically, atoms fall into the class of molecules) will combine without heating. They can simply be put close to each other (i.e.: mixed in liquid, air passing over a solid, etc. whatever), although there must be some heat, such that it is not absolute zero, because if it's absolute zero the molecules are not moving, but absolute zero cannot be achieved according to the laws of thermodynamics. The question of whether there are "few or many" is rather vague. It could be a question of how many types of molecules will combine without heating and under what conditions, or it could be a question of how many molecules in the Universe or on Earth can do this, but it's not that useful a question anyway.

The bonds between atoms in a molecule can be broken by inducing atoms to bond instead with another molecule by just putting them together, in the same way as above, or by adding some energy to the molecule, like light or heat, so that the bonds break.

In all cases, the exact temperature for every reaction might be different depending on the molecule, so one cannot say universally that all reactions will take place "at room temp" or not, or whatever. I suggest you pick up a basic General Chemistry textbook and check it out. Note also that the way the universe actually works is probably more crazy than you have ever imagined. - Centrx 05:58, 23 Dec 2004 (UTC)

macromolecules

From the article: "An example of a macroscopically-sized molecule is DNA, a macromolecule" Being a macromolecule has nothing to do with being macroscopic. You could manufacture a DNA molecule that was long enough to become a macroscopic object, but must DNA molecules are microscopic objects. Memenen 14:21, 27 Dec 2004 (UTC)

• Good point. I have edited the DNA example. Does is sound good? --Unconcerned 05:49, 28 Dec 2004 (UTC)

Intro Paragraph

Abstractly, a single atom may be considered a molecule, as it is when referred to collectively with molecules of multiple atoms, but in practice the use of the word molecule is usually confined to chemical compounds, of multiple atoms.

I am removing this from the article -- Not only is it confusing, but it contradicts the preceeding definition of molecule (two or more atoms, or before a previous edit, multiple atoms). Tygar 06:55, Feb 25, 2005 (UTC)

This is an older discussion. By definition, molecules -- the smallest particles of a compound that still preserve its chemical and physical properties -- can consist of one atom or more atoms bonded together. It is still a valid definition that can be found in most, if not all, chemistry and physics textbooks. A peculiar use of the term molecular is as a synonym to covalent, which probably arises from the feeling that ionic bonds do not usually yield well-defined "smallest particles" consistent with the definition above. However, a whole chapter of physics, dealing with thermodynamics and the kinetic theory of gases, consider monoatomic gases as composed of single-atom molecules (examples: monoatomic+molecule (http://www.google.com/search?q=monoatomic-molecule) and monatomic+molecule (http://www.google.com/search?q=monatomic-molecule)). Therefore, I feel that the article should include all aspects of the subject discussed as opposed to just a peculiar one and as such re-included the fragment above. The discussion remains open, though.--Unconcerned 17:33, 30 Mar 2005 (UTC)

Avogadro's Law is stated a couple of times in the Wikipedia [1] (http://en.wikipedia.org/wiki/Avogadro%27s_law) & [2] (http://en.wikipedia.org/wiki/Avogadro)

"equal volumes of gases, at the same temperature and pressure, contain the same number of molecules"

Therefore the noble gases (He, Ne, Ar etc) are made up of atoms that can also be described as monatomic molecules. There are intermolecular forces of attraction between the atoms of noble gases and they follow all the gas laws as do other simple molecules.

I agree with Unconcerned.

DNA Example

I believe that the DNA visibility example is useful in providing a feeling about the size and tangibility of molecules, and in making the concept less abstract. The way it was formulated also allowed for a few useful wikilinks. Therefore, I re-included the removed fragment.--Unconcerned 17:33, 30 Mar 2005 (UTC)

To Do / Wish List

1. Discussion on how spectroscopy methods are used to ellucidate molecular structures