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400 BCE
Democritus
Democritus’ atomic theory posited that all matter is made up of small indestructible units called 'atoms'. -
400 BCE
Democritus' Model
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Dalton
Dalton believed in Democritus work. His theory consisted of 4 main ideas.
- All matter is composed of atoms that are invisible
- All atoms are identical in size and mass
- Atoms are rearranged at chemical reactions occur
- They can not be created or destroyed -
John Dalton's Model
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Thomson
J.J. Thomson came up with the “plum pudding” model of the atom in 1904. It differed to that of Democritus in that it acknowledged that atoms consisted of both positive and negative particles. -
Thomson's Model
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Rutherford
Rutherford proved Thomsons' atomic model to be incorrect. He proved the existence of protons with his famous gold experiment. This experiment was performed by shooting alpha particles at gold foil and observing where they hit. -
Rutherford's Model
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Bohr
In 1913, Nelis Bohr created a new model of an atom. It consisted of electrons that orbited around the nucleus in shells. -
Bohr's Model
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Present Day
In 2012 there was the discovery that photon particles can bind to create molecules. A god particle (particle that gave other particles mass) was discovered and called the Higgs Boson. The current model of the atom looks a bit like the solar system, with electrons orbiting a nucleus made up of protons and neutrons.
