hoyo-damon-period1

aristole

200

real date 300 b.c The scientist Aristotle developed this idea of basic building blocks. He actually disagreed with the very idea of atoms and thought that everything was made of 5 elements- air, fire, water, earth, and aether

democritus

200

500 B.C) The scientist Democritus was responsible for this model of the atom. It was the first model of the atom ever to have been thought of and was accepted in 400 B.C. He didn't conduct a specific experiment to develop this model, he just thought that there must be some sort of building block that makes everything up. He was, of course, right. He thought that the atom was a tiny ball that could not be physically divided. The model was kind of like a tiny marble

Henri Becquerel

Jan 1, 1896

1896 Henri Becquerel discoverd radioactivity while he was experimenting with Uranium salts

marie and pierre curie

Feb 1, 1898

1898 marie and pierre curie discovered that the ability of atoms to radiate did not depend on the arrangement of the atoms; that it actually depended on the interior of the atom. They also found that only uranium and thorium gave off this radiation. This of course changed the whole idea of atoms and radiation

john dolton

Apr 13, 1900

1900 simiar to democritus's theory but dolton thought that all elemetns were diferent because they had different masses

J.J Thomas

Oct 13, 1904

1904 J.J Thomas discovered the electron " the plum pudding" model

Robert Millikan

Sep 15, 1909

1909 millikan discovered the charge of an electron by using the falling drop method.

ernest Rutherford

Oct 13, 1911

1911 Rutherford use his gold foil experiment to understand the atom

Niels Borh

Oct 13, 1913

1913 Borh based his theorty off of rutherfords theory by doing that he discovered the atomic nucles.

James Chadwick

Sep 9, 1932

1932 Chadwick discovered the neutron