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400
Democritus
The theory of Democritus said that everything is composed of atoms, which are physically, but not geometrically, indivisible. Between atoms there lies empty space.Atoms are indestructible and there an infinite number of atoms. -
Period: 400 to
5 Scientists
A -
John Dalton
1803 - 1805
He was one of the first to develop an atomic model. He thought that the atom was the smallest possible component of matter. -
JJ Thompson
He showed that Cathode Rays were unknown negatively charged particles that were smaller than the atom. These particles are now known as Electrons. -
Ernest Rutherford
He post suggested that the nuclear structure of the atom that Rutherford experimented showed that when alpha particles are fired into gas atoms few are violently deflected, which implies that a dense, positively charged central region contained most of atomic mass. -
Robert Millikan
In his famous oil drop experiment he replaced water(which tended to evaporate too quickly) with oil -
James Chadwick
Chadwick discovered electrically neutral particle with a similar mass as a proton. He discovered Neutron. -
Neil Bohr
His theory stated that electrons travel around the nucleus in definite paths and fixed distances. Also electrons can jump from one level to a path to another level
