El Desarrollo De La Teoria Atomica

I. History and Development of the atomic theory.
Democritus

Nationality- Greek
Time of contribution- sometime in the fifth century BC.
Discovery or contribution to the atomic theory-He iscredited with inventing
the concept of the atom.

Aristotle

Nationality- Greek
Time of contribution-384 B.C
Discovery or contribution to atomic theory- He believe that all matter was createdof water, fire, air and earth and that it came in different forms. Aristotle felt that regardless of the number of times you cut a form of matter in half, you would always have a smaller piece ofthat matter.
John Dalton

Nationality- British
Time of contribution- 1803
Discovery or contribution to the atomic theory- Dalton created the atomic theory. The theory proposed a number of basicideas:
All matter is composed of atoms
Atoms cannot be made or destroyed
All atoms of the same element are identical
Different elements have different types of atoms
Chemical reactions occurwhen atoms are rearranged
Compounds are formed from atoms of the constituent elements

J.J. Thomson

Nationality- British
Time of contribution- 1897
Discovery or contribution to the atomictheory- J.J. Thomson identified electrons in matter by his cathode ray tube experiment. He deducted that electrons were components of all matter and calculated the charge to mass ratio for the electron.Robert Milikan

Nationality- American
Time of contribution- 1909
Discovery or contribution to atomic theory-He determined the charge on electrons by doing an oil drop experiment.




ErnestRutherford

Nationality- British
Time of contribution- 1909
Discovery or contribution to the atomic theory-Through the Gold Foil
Experiment he discovered that when Gold Atoms were deflectedoff of tin foil
that some of them must have bounced because of a dense center in the
atoms (the nucleus). Basically he discovered the nucleus.

James Chadwick

Nationality- British
Time of...