[chimico]

Hello, I read that equal volumes of different gas contain the same number of molecules so if I solidify that gases they will occupe different volumes?

How do we know that for example H contain 1 electron 1 proton and 1 neutron, E contain 2 , Li 3, Be 4 and etc..?
is it a consequence of a reasoning or they were counted sperimentally? how?

Thanks!

[Vidya]

Experimentally they have proved it .
Just read all experiments done to prove structure of an atom.

[vmelkon]

Hello, I read that equal volumes of different gas contain the same number of molecules so if I solidify that gases they will occupy different volumes?

How do we know that for example H contain 1 electron 1 proton and 1 neutron, E contain 2 , Li 3, Be 4 and etc..?
is it a consequence of a reasoning or they were counted experimentally? how?

Thanks!

That was an assumption made by Avogadro. The assumption used common sense. You take 1 mL of water and you boil it and you get a whole lot of gaseous water. Therefore, the distances between the molecules is immense. The molecules run around  free with intermolecular forces being small. Avogadro isn't exactly correct because there are differences between gases but it was good enough to advance experimental chemistry.

I believe that they started out with electrochemistry to compare how many grams of hydrogen do you get when you use 1 A for 1 hour? How many grams Lithium can you get for 1 A for 1 hour?

Besides that, they use to measure the relative amount of C and H and O and N in different organic compounds. They assumed that the the smallest integer amount of each would represent the molecule of a given organic compound. Example, propane would be C3H8 and not C6H16 or anything higher.

The nuclear physics came along and mass spectroscopy and other techniques to validate those early assumptions.

And I think that even after Avogadro's days well into 1899, people weren't sure that atoms existed. Atoms and chemical formulaes were considered just chemist tools to discuss experiments. By 1899, there was a lot of experimental data and the periodic table was developed and it became clear that the stuff in our world is made of a few "elements" and these come together to make the thousands of compounds (by today's number, 25 million).

[vmelkon]

There are many assumptions to consider. And chemicals would really react to any procedure. Like when you boil water, there are particles or gaseous water that would occur. Or, water would also evaporate. Knowing the number of molecules could also be known by means of the equation and also by experimentation.

Which assumptions? Water boils and so what? Water evaporates and how does that help?

Which equation?

[fledarmus]

This should be a good starting point for you:

http://en.wikipedia.org/wiki/Avogadro%27s_number

Follow the footnotes in the history section - they will take you to the experimental methods used to determine Avogadro's number.