-
101
Democritus ~ 429 BC
First person to think of the atom.
Thought atom was a solid sphere. -
102
Aristotle ~ 400 BC
Thought everything was made of air, earth, water, and fire.
Didn't think things were made of atoms like Democritus did. -
Sir Isaac Newton
Tiny pieces of mass "swimming" around. -
Dalton
- Matter-composed of atoms. (T)
- Atoms-can't be destoyed or made. (F)
- All atoms of same elements are identical. (F)
- Different elements = different atoms (T)
- Chemical reactions occur when atoms are rearranged. (T)
- Compounds are formed from atoms of a different elements. (T) Thought that the atoms was a circle.
-
Becquerel
Helped discover radioactivity.
Thought atom was a solid sphere. -
J.J. Thomson
Discovered negative particles. -
Robert Andrews Millikan
Measured the mass and charge of an electron. -
Rutherford
Gold foil experiment.
Proved nucleus was in the middle of the atom and electrons surround it. -
Bohr
Depicted atom as small, positively charged nucleus surrounded by electrons. -
Francis Aston
Discovery of isotopes of non-radioactive elements. -
Erwin Schrodinger
Consists of nucleus and clouds.
Discovered formula that calculated the odds of where an electron might be.
Proved Bohr incorrect. -
Chadwick
Discovered the neutron.