-
400
Democritus
He created the first model of an atom. He was the first to even think about an atom. -
400
Aristotle
He opposed Democritus theory. Only 4 elements: earth, fire, air, water. -
500
Leucippus
He figured out that everything is made up of something. -
Isaac Newton
Created the three laws of motion; no atom. -
John Dalton
Atomic Theory
1. All matter is made of atoms. They are invisible.
2. All atoms of the same elements are different. (false)
3. Atoms combine to make compounds.
4. Atoms are rearranged- not created or destroyed in a chemical reaction. -
JJ Thomson
Discovered electron after others thought there were particles that made up an atom. He used cathode ray tube to discover electron. He also made the plum pudding model. -
Ernes Rutherford
Atoms have positive charges in a small, but dense nucleus. He did this through "gold foil experiment". -
Niels Bohr
He discovered electron travel on rings (energy levels). The more rings, the higher the energy level. They can move from ring to ring, but it takes energy. -
Schruedinger
Described a cloud- like region where an electron is likely to be found. -
John Chadwick
He discovered the neutron (noticed odd diference in masses). -
Thales of Miletus
Miletus noticed static. He paved the way for future discoveries.
