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400 BCE
Democritus
He believed that matter was composed of tiny indivisible particles called atoms. He also believed that they came in different shapes and sizes. -
John Dalton
With experimental evidence he believed that matter is composed of small indivisible particles (atoms). And that chemical reactions are rearrangement of atoms. -
J.J. Thomson
Thomson's model was called Plum Pudding Model. He placed two oppositely-charged electric plates around the cathode ray. He began to call these cathode ray particles electrons. -
Ernest Rutherford
His experiment is now known as the nuclear model. He concluded that all of the positive charge and the majority of the mass of the atom must be concentrated in a very small space called the nucleus. -
Niels Bohr
He investigated how light was emitted from Hydrogen when it was excited. He also explained that electrons could jump from one orbit to another by losing or gaining energy. -
Erwin Schrodinger
The biggest difference that was discovered after Bohr's model was released was the idea that identifying the specific location of the electrons could only be identified through probability of finding them in an area around the nucleus. The big thing is that the orbitals do not look anything like the energy shells that Bohr proposed.