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Democritus
Democritus came up with the idea of an atom. He was from ancient Greece. He believed if you cut a piece of silver in half, at some point, you'd end up not being able to cut anymore. -
John Dalton
John Dalton had a theroy in the late 1700s. This theory had 3 parts. Alll substances are made of atoms, they’re too small to be created, divided, or destroyed, and atoms of the same element are exactly alike, and atoms of different
elements are different.
∙atoms join with other atoms to make new substances. -
J.J Thomson
J.J. Thomson had a new theory, and created a Cathode- Ray Tube. The beam had to have particles that were negative. He named them "corpuscles" that are now known as electrons. To balance the negative charge, there had to be a positive charge. His model of the atom is known as the Plum-Pudding model. -
Ernest Rutherford
Rutherford's expirement was that he had to aim positively charged particles at a thin sheet of gold foil. A lot of the particles passed through, but some were deflected, and bounced back. In 1911, he figured out the gold foil's was 100,000 smaller than the atom. -
Niel Bohr
Niel Bohr discovered that electrons travel around the nucleus in definite paths. The paths are in certain distances from the Nucleus. He thought that possibly electrons can "jump" from a path in one level to a path in another one. -
Modern
Now, we have figured out that electrons do not travel in definite paths. They're likely to be found in an electron cloud.
