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Antoine Lavoisier
Antoine Lavoisier discoevered conservation of mass. Mass (and atoms) can not be created or destroyed, they can simply be changed. -
John Dalton
John Dalton developed his atomic theory. 1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms. -
J.L. Gay-Lussac
Joseph Louis Gay-Lussac found that under constant conditions, the volumes of reacting gases and gaseous peoducts are in the ratio of small whole numbers. -
Amadeo Avogadro
Avogadro stated that egual volumes of gases, under the same conditions, have the same number of molecules. -
Joseph Proust
Joseph Proust discovered the law of definite proportions. Specific substances always contain elements in the same ratio by mass. -
Henri Becquerel
He found that matter containing uranium exposes sealed photographic film. -
Marie and Pierre Curie
Used Becquerel's discovery that uranium exposes sealed photographic film to find out that rays are given off by uranium and radium. -
J.J. Thomson
He discovered cathode rays consist of electrons through skillful research and also he discovered protons. -
Max Planck
He assumed that energy was given off in quanta and that one quantum of enrgy was related to the frequency by the equation E=hv. -
Robert Millikan
Robert Millikan obtained the first accurate measurement of an electron's charge. -
Henry Moseley
He discovered that the wavelength of the X rays is characteristic of the metal used as the anode. It depends on the the number of protons in the nucleus. The number of protons determines the identity of the element and the number of neutrons determines the particular isotope of the element. -
Niels Bohr
Bohr introduced his model of the atom in which a positively charged nucleus is surrounded by moving electrons. -
Albert Einstein
Einstein developed his theory of relativity: E=mc^2 or energy = mass x the speed of light. This was all based on his hypothesis that mass and enrgywere equivalent. -
Lord Rutherford
He predicted the existence of neutrons. -
Louis de Broglie
He used Einstein's theory of relativity and Planck's quantum theory to make an expression that enabled him to predict the wavelength of a particle of mass and velocity.
