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Chem Atoms
Term | Definition |
---|---|
Democritus | 4 B.C. -created the concept of atoms -reasoned that atoms were indivisible and indestructible Atomic Model |
Dalton | 1766-1844 DALTON'S THEORY: -all elements composed of tiny particles called atoms -atoms of same element are identical; atoms of different elements are different |
Dalton (cont.) | -atoms of different elements can mix physically or combine chemically to form compounds -chemical reactions cannot change atoms of one type of element to another but can for atoms of different elements |
Eugen Goldstein | 1850-1930 -discovered positively charge particles in 1886 -used a cathode ray tubes -the ray produced was deflected by an electrical field (showed that atoms had particles with (+) charge) |
J.J. Thomson | 1856-1940 -discovered electrons in 1897 -used a cathode ray tube -the ray produced was deflected by an electrical field (showed that atoms had particles with (-) charge) Plum-Pudding Model |
Rutherford | 1871-1937 -Gold Foil Experiment -names positively charged particles as Protons -discovered the nucleus in 1911 -suggests nucleus made of protons Nuclear Model |
James Chadwick | 1891-1974 -discovers the Neutron and Neutrons mass in 1936. |