Democritus		Particles have characteristics of waves - the electron stream acted in the same way as a ray of light.
John Dalton		Law of Definite Proportion: Specific substances always contain elements in the same ratio by mass
Antoine Lavoisier		"Planetary Model" - electrons orbit the nucleus
Joseph Proust		subjected a thing sheet of fold foil to a stream of subatomic particles - concluded most of the atom is empty space
J.L. Gay-Lussac		Heisenberg Uncertainty Principle: impossible to know the exact position and momentum of an object at the same time.
Amadeo Avogadro		cations and anions
Michael Faraday		initiated spectroscopy: study of substances exposed to some sort of continuous exciting energy - Planetary Model
Svante Arrenhus		"Atoms" - Greek for indivisible World composed of two things: Empty space and tiny particles (atoms)
GJ. Stoney		worked with gas reactions at constant temperature and pressure
JJ Thomson		concluded quantum and quanta and created Planck's Hypothesis: energy is given off in quanta (little packets of energy) instead of continiously
Robert Milikan		no. of protons of the lement is the atomic number, known as the letter Z
Walter Bothe		"a hard dense sphere"
James Chadwick		Law of Conservation of Mass: ordinary chemical reactions, matter can be changed in many ways, but it cannot be created nor destroyed
Henry Mosley		treated electron as a wave and developed a mathematical equation to describe its wave-like behavior.
Hans Geiger and Enest Marsden		believed element is composed of like atoms- *the atom is a hard dense sphere* Law of multiple proportions: ration of masses of one element combines w/ a constant mass of another element can be expressed in small whole numbers
Rutherford/Bohr		obtained the first accurate measurement of an electron's charge - proved it was possible to calculate the actual mass of the electron
Max Planck		First evidence of the particle
Louis Debroigle		researched the cathode ray: anode is the positive terminal and teh cathode is the negative terminal. Measured the ratios of charge to the mass of the electron and said atom's mass is positive containing electrons.
Wener Heisenberg		High energy particles w/ no charge and w/ the essentially the same mass of the proton ~ neutron. isotopes contain the same no. of protons but a different no. of neutrons
Scroedinger		Equal volumes of gases, under same conditions, have the same number of molecules
Dalton		substances in water ->> electric current
Rutheroford-Bohr		Named the electron
Scrhroedinger		electrons move at speed of light so it appears they occupy all the space around the nucleus