History of the Atom

Democritus

460

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he used theoretical resoning for his experiments
he discovered that all matter has atoms

John Dalton

May 26, 1803

imagehe experimened that all matter is composed of veary small particles
he discovered what an atom has in properties

Henri Becquerel

Dec 15, 1852

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he accedentaly discovered radio activity in an experiment

William Crookes

Jan 28, 1861

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he experimented on something more than just a ray
he helped discover the electron

Ernest Rutherford

Jan 28, 1907

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he discovered the nucleus of an atom

Niels Bohr

Jan 28, 1911

he experimented on positive rays
he discovered energy levels of electrons

James Chadwick

Jan 28, 1932

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he experimented on alpha particles that project towrds berylilium
he discovered nutrons

Sir Joseph John Thomson

Jan 28, 1937

imagehe experimented on electrons
he discovered the electron

model currently used

Jan 28, 2013

imagethe model exepted as the one we use today is rutherford's