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450
Democritus
first to suggest the existence of an atom -
Jan 1, 600
Aristotle
Opposed Democritus's theory thought that matter was 4 elements combined. -
Antonio Lavoisier
Changed science from observations to actual meausurement,allowing you to predict; also proved multiple compounds -
John Dalton
gave the first true model of what he believed an atom looked liked. -
Henri Becquerel
discovered certain elements give off unique matter -
J.J Thomson
Gave the idea that the atom was mainly positve matter with little spots of negative energy; known as the plum atom -
Max Planck
Quantum theorm; deals with the smallest form of matter able to be measured -
Ernest Rutherford
mainly empty space, most energy is positve and located in the core (nucleus) and that the electrons move around the nucleus -
Neils Bohr
quantum mechanics; proposed that elctrons had a unique orbit around the nucleus -
Henry Mosley
Discovered charges in the nucleus. and that the atomic mass is the same amount as protons. -
Robert Millikan
Calculated the mass of an electron (charge:mass) (one negatifve:1/1840 hydrogen atom) -
Erwin Schrodinger
Wave Mechanics; Delevoped the math equation for the electrons motion and created the cloud model of the atom. -
Werner Heisnberg
Created the "Uncertainty Principle"- determined the properties of particles; You can't determine the monmentum and position at the same time. -
James Chadwick
Discovered and confirmed that the neurtron existed.
