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John Dalton put two elements together and called them atoms.
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The British physicist Joseph John (J. J.) Thomson discovered the electron in a series of experiments designed to study the nature of electric discharge
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In 1902 Lenard showed that an electron must have a certain minimum energy before it could produce ionisation when it passed through a gas
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Ernest Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus
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Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus.
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In 1932, Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons - elementary particles devoid of any electrical charge.
