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101
Democritus- 429 BC
First person to think of the atom.
Thought atom was a solid circle. -
101
Aristole- 400 BC
He thought everything was made of fire, earth, air, and water. -
Sir Isaac Newton- 1704
He thought there were tiny pieces of mass. -
John Dalton- 1766
He came up with the atomic therapy.
All matter is composed of atoms. true
Atoms can not be made or destroyed. False
All atoms of the same element are identical. false
Different elements have different types of atoms. true
Chem. reactions occur when atoms are rearranged. true
Comp. are found from atoms of different elements. true -
Henri Becqueal- 1896
He helped discover radioactivity. -
JJ Thompson- 1897
Discovered electrons. -
Robert Milikan-1908
He measured the charge of a single electron. -
Rutherford-1911
Discovered that an atom has a central positive nucleus. -
Neils Bohr-1913
Discovered the Bohr model. -
Francis Aston-1920
Discovered isotopes and identified 212 natural isotopes. -
Erwin Shrodinger-1926
Discovered the formula that caculated the odds of where an electron might be. -
James Chadwick-1932
Discovered the Neutron.