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550
Parmenides
Everything made of building blocks. *550 BC -
Period: 550 to
The Atom
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Sep 18, 600
Democritus
Everything is made of atoms. *400 BC -
Sep 18, 650
Aristotle
No one argued, all matter was fire, water, earth, air. *350 BC -
Dalton
Dalton's Atomic Theory
1) All elements composed of indivisible atoms
2) Atoms of the same element are the same. Atoms of different elements are different.
3) Atoms make compounds.
4) Atoms are rearranged in chemical reactions. Not created. Not destroyed. Not changed -
Dmitri Mendeleev
First periodic table, sorted by weights, left gaps. Elements filled in the gaps later! -
J.J. Thomson
Discovered the electron existence, but no details "cathode ray tube" -
Millikan
Found charge of electron (1/2000 of atom), mass of atom -
Ernest Rutherford
Positive (protons) nucleus with electrons around. The nucleus was very tiny and very dense. -
Gold Foil Experiment
Shot alpha particles at golden foil. They should habe gone straight through, but some bounced off showing there was a nucleus, and the rest was empty space. -
Niels Bohr
Electrons orbitted in rings (energy levels), could jump from orbit to emit energy -
Chadwick
Discovered neutron (masses weren't making sense) -
Manhattan Project
Nuclear research, created atomic bomb for WWII, separated the atom. -
Cloud Model
Shroedinger- electrons are not necessarily -
Sheldon
BAZINGA!!!!