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John Dalton
Atoms are invisible units.
All atoms of a given element in mass and properties
compounds are formed by a combination of two or more different kinds of atoms
A chemical reaction is a rearrangement of atoms -
J. J. Thomson
Created the "Plum Pudding Model". used a cathode ray tube to discover electrons -
Robert Milikan
Milikan measured the charge of electrons. He used a perfume bottle to spray water or oil droplets into a sample chamber. The droplets fell through a pin hole between two plates of an electric field. In the chamber the electrons where removed from the molecules in the air. By studying each drop he was able to show that the charge on a drop.The mass of an electron is at least 1000 time smaller tht the lightest atom -
Albert Einstein
He proposed that light energy can be absorbed or emitted only in discrete packets call quanta, a proactive contradiction of the then-prevalent] wave theory of light. He also mathematically proved the existence of atoms and that hep revolutionize all the sciences. -
Marie Curie
Cuire studied other elements to see if they emitted radiation. This is how she figured that radioactiity dose not depend on how atoms are arranged into molecules, but rather than its originates with the atom it self. It was a very important discovery in scientific history. -
Ernest Rutherford
Gold foil experiment. Alpha particles were placed in a small lead box with a small hole, any alpha particles that escaped the box followed a straight path to the foil -
Niels Bohr
He created the planetary atom.
Electrons assume only certain orbits around the nucleus
each orbit has an energy associated with it
lights is emitted when an electron jumps from a higher orbit to a lower orbit -
Ernst Schrodinger
Made the quantum mechanical model. His theory was that electrons absorb and emit radiation of fixed wavelengths when jumping between the fixed orbits around the nucleus. Assuming that matter could be regard both as particles and as waves. so he created an accurate equation to find the energy levels of atoms. http://www.nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-facts.html -
James Chadwick
James showed that the reaction, a neutral particle with the mass about that of a proton, was emitted. He discover the neutron.