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300
Aristotle-300 B.C
There was only four elements that existed. Those elements were fire water air and earth. All matter was composed of these four elements. All elements and matter only had four characteristics as well. The characteristics included hot,cold,dry and wet. -
430
Democritus-430 B.C
Democritus was a Greek philosopher. Democritus believed that ALL matter was made up of atoms. Atoms were the simplest part of matter. Democritus came up with the word "atom" through the Greek word "atoms" meaning indivisible or indestructible. -
A.L Lavoisier-1778
A.L was a French nobleman and chemist. He was known as the "Father of Modern Chemistry". A.L noticed,discovered,and named "Oxygen". -
John Dalton-1803
John Dalton was an English Chemist and school teacher. He created "Dalton's Atomic Theory." This theory contains evidence that all matter is composed of atoms. Which John Dalton believed were indivisible. -
William Crooks-1861
William was a British physical chemist. Crooks discovered Thallium. -
The Curies-1898
Marie and Pierre Curie (husband and wife) discovered and isolated Radium and Polonium. -
Max Planck-1899
German theoretical physicist, he discovered the "Planck constant". A physical constant that is quantum of action in quantum mechanics. (E=hr) -
Ernest Rutherford-1911
Rutherford was a physicist from New Zealand. He found that an atom has a small dense and positively charged nuclear. Also, that electrons move around that nuclear. -
Neil's Bohr-1913
Bohr was a Danish physicist. He made the Bohr atomic model that showed electrons move in a circular orbit at fixed distances from the nucleus. -
Robert Millikan-1913
Millikan was an American physicist. He discovered the charge and mass of an electron by using a single oil drop. -
Erwin Schrödinger-1926
Schrödinger was an Austrian physicist that developed mathematical equation to describe the motion of electrons in atoms. It lead to the electron cloud model. -
Hans Geiger-1928
Geiger was a German nuclear physicist that invented the Geiger Counter to measure radiation with Ernest Rutherford. -
James Chadwick-1932
English physicist discovered the neutron which has no/equal charge -
Lise Meitner-1938
She was an Austrian physicist who worked on radioactivity and nuclear physics. Along with Otto Hahn and Fritz Strassman became the first to recognize that the Uranium atom when bombarded by neutrons actually split. This is known as nuclear fission. -
Glen T. Seaborg-1940
He was a nuclear chemist from the United States. He discovered Plutonium.
