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Dalton's Atomic Theory
first atomic theory, first scientific evidence that the atom exists -
James Clerk Maxwell
Proposed electric and magnetic fields filled the void. -
Cathode Ray Tube Experiments
JJ Thompson discovered that an electrical current passed through gases at very low pressure in a glass tube. These experiments led to the discovery of the electron. -
Plum Pudding Model
JJ Thompson discovered a way to explain why most atoms are neutral. -
Albert Einstein
published the famous equation E=mc2 -
The Atomic Nucleus
In Rutherford's Gold Foil Experiment, he discovered that fast moving alpha particles were shot at a thin piece of gold foil. Most went straight through the foil with only a slight deflection. He concluded that there was an existence of a very small, dense, positively, charged nucleus that contains most of the atom's mass, but occupies an insignificant fraction of it's volume. -
Robert Millikan
Oil drop experiment determined the charge (e=1.602x10-19 coulomb) and the mass (m=9.11x10-28 gram) of an electron. -
Ernest Rutherford
Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil . He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus. -
Composition of the Nucleus
Rutherford, "the proton"- a positive charge equal in magnitude to the negative charge of an electron and about the same mass as a neutron. -
Niels Bohr
Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. -
de Broglie
Discovered that electrons had a dual nature- similar to both particles and waves. Particle/wave duality. Supported Einstein. -
Werner Heisenberg
Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle. -
Erwin Schrodinger
Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. -
Composition of the Nucleus
The Neutron: (Chadwick)- electically neutral, slightly heavier than a proton. -
Enrico Fermi
Conducted the first controlled chain reaction releasing energy from the atoms nucleus.