Chemistry Theories

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7 Cards. Created by Josey ().
Democritus, John Dalton, JJ Thomson, etc.


Greek philosopher believed that matter is composed of atoms. He believed they were indivisible, indestructible, and homogenous. Have different sizes and shapes which determine their properties.

John Dalton

Atomic Theory. Matter is composed of small particles called atoms. Atoms are indivisible and indestructible. Atoms of an element are identical in size, mass, and chemical properties.

JJ Thomson

concluded that cathode rays consist of electrons. All atoms must have electrons

Robert A. Millikan

Experiments showing the mass of an electron. The mass of the simplest type of hydrogen. A single electron carries a charge of -1

Lord Kelvin

Plum Pudding Model. Atom a uniform structure of positive charge with negative electrons to balance the positive charge without.

Ernest Rutheford

Gold foil experiment. Alpha particles through gold foil. SOme deflected, sme passed through. Concluded nucleus is a dense center with a positive charge surrounded by electrons.

James Chadwick

Nuclei also contain a neutron.