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400 BCE
Democritus
He started the idea of atoms. He said that if a substance was repeatedly divided it would reach a point where it cant be divided anymore. He said that matter is made of tiny solid particles named atoms, which means "uncuttable". -
John Dalton
He was a teacher in England. Did chemistry as a hobby. spent a lot of time examining chemical reactions. He noticed that new substances always formed in mathematical ratios. -
J.J. Thomson
Discovered that atoms contain negatively charged particles called electrons. In his model, the electrons floated outside of the atom. his model was called the raisin bun model -
Ernest Rutherford
He did a series of famous experiments that involved shooting a beam of particles at a piece of thin gold and seeing what happens. The data showed that an atom is mostly empty space, with the electrons moving around a dense positively charged center. he called that the nucleus. he also named the positively charged particles protons. -
Niels Bohr
Used Rutherford experiment data to show that the electrons move around the nucleus in particular energy levels according to the amount of energy they have. Electrons closer to the nucleus have less energy while electrons further away have more. -
Werner Heisenberg
He is known for his uncertainty principle and the theory of quantum mechanics. -
Erwin Schrodinger
He took the Bohr model to the next level and used mathematical equations to describe the likelihood of finding an electron in a certain position. -
James Chadwick
He was a partner of Ernest Rutherford, and he discovered a second particle in the nucleus. He called that second particle the neutron.
