Scientists contribution to help us understand atomic theory. :
- John Dalton 1803: All elements are made up of atoms
- JJ Thomson 1897: discovered electrons is negatively charged.
- Rutherford 1898 -1911: Estimated size of atom and concluded that mass of atom is concentrated in the nucleus.
- Niels Bohr 1922: explained that electrons are found at the edge of an atom. electrons are orbiting nucleus. Protons and neutrons are found in the nucleus.
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