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Democritus
Democritus claimed that everything is made up of atoms and the atoms are physically but not geometrically indivisible.
And the atoms are indestructible -
john Dalton
- Elements are made of extremely small particles called atoms.2. Atoms of a given element are identical in size, mass and other properties. atoms of different elements differ in size, mass and different properties.3. Atoms cannot be subdivided, created, or destroyed.4. Atoms of different elements combine in simple whole number ratios to form chemical compounds.5. In chemical reactions atoms are combined, separated or rearranged
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Sir Joseph John Thomson
he discovered electrons and isotopes and he invented the mass spectrometer. In 1905 he discovered the radioactivity of potassium.In 1906 Thomson demonstrated that hydrogen had only one electron in per atom. -
Ernest Ruthorford
His atomic theory was he proved that radioactivity involved the transmutation of one chemical element to another. He also believed that atoms have their charge concentrated in a very small nucleus. -
Erwin Shrodinger
His theory was that electrons are arranged in concentric circular orbits around the nucleus. This model is patterned on the solar system and is known as the planetary model. -
niels Bohr
His atomic theory was the bohr model of an atom with the atomic nucleus at the Centre and electrons in orbit around it which he compared to planets orbiting the sun. -
James Chadwick
His atomic theory was he made a fundamental discovery in the doorman of nuclear science he proved the existence of neutrons.
