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400
Democritus
He stated that all matter consists of individual particles called atoms. He also realized atoms were solids, but invisible and very small. Atoms differ in shape, size, mass, position, and arrangement. 400 B.C. -
John Dalton
He discovered that all elements were made up of atoms. He made the idea of an atom useful. -
Thomson
He stated that atoms were not simple, solid spheres. He discovered electrons, electrons are small, negatively charged particles. -
Einstein
He published the famous equation- E=mc2; mass- energy equivalence. -
Rutherford
He developed a more complete understanding of the structure of atoms. He discovered that atoms were mostly made of space since most of the particles he was shooting could pass through the gold foil. He decided the center of the atom was positively charged, and called it the nucleus. He said positively charged atoms were in the nucleus, negatively charged atoms were scattered about the perimeter. -
Bohr
He proposed that electrons orbit AROUND the nucleus. He stated each electron has a set amount of energy. -
Schrodinger
He took the Bohr Atom Model one step further. He used mathematical equations to describe the possibility of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. It doesn’t pinpoint the exact location of an electron, it gives locations of where it could possibly be. -
Heisenberg
He developed a model of proton/ neutron interaction; he discovered more info on the nucleus.