-
101
Democritis- 429 BC
First peron to think of the atom.
Thought atom was a solid circle. -
101
Aristotle- 400 BC
Everything is made from four elements. Fire, Air, Earth, and Water. -
Sir Issaac Newton
Tiny pieces of mass "swam" around. -
John Dalton
Atomic Theory.
1. All matter is composed of atoms. true
2.Atoms can not be destroyed. false
3. All atoms of the same elements are identical. false
4. Different elements have different types of atoms. true
5.Chemical reactions occur when atoms are rearanged. true
6. Compounds are formed from atoms of different elements. true -
Henri Becquerel
Radio activity. -
J.J. Thompson
Proved the exsitence of negatively charged atoms. -
Robert Millikan
Measured Charge of single electron.
Measured mass of electrons. -
Rutherford
Atoms have a central positively charged nucleus surrounded by negatively charged obiting electron. -
Neils Bohr
Bohr Model- Electron travel in a circular orbit -
Francis Aston
Isotopes non-radioactive -
Erwin Shrodiner
Atom has a nucleus shell formula -
James Chadwick
discovered Nuetron