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Period: 427 BCE to 427 BCE
Plato
Plato introduced atomic theory -
Period: 400 BCE to 400 BCE
Democritus
Theory that atoms were indestructible, hard, and move through infinant numbers through space. -
Period: 384 BCE to 384 BCE
Aristotle
Aristotles' theory was matter is made out of atoms. -
Period: to
Lavoisier
Started theory of chemical reaction to oxygen. -
Period: to
John dalton
Found out atoms from an element are different from atoms of another element -
Period: to
The Alchemists
All metals are made up from two principals. mercury and sulfer -
Period: to
Newlands Law of octaves
When elements are ordered from low to high mass, every 8th element is a repetition of the properties of the starting element. -
Period: to
Robert Millikan
Birth of Robert millikan physicist -
Period: to
Mendeleev's Pd. Table
Created periodic table thinking element properties are a periodic function of their atomic weight. -
Period: to
Photoelectric Effect
Heinrich Radolf Hertz discovered when ultraviolet light shines on two metal volteges and the light changes voltege. -
Period: to
Discovery of Radioactivity
After opening a drawer Henri Becquerel discovered spontanious radioactivity -
Period: to
Discovery of electron
Found out by J.J. Thomson -
Period: to
Planck's Quantum Theory of Light
Light exists as tiny massless particles called photons with properties of a wave and partical -
Period: to
Plum Pudding Model
Supposed to look like a plum made by J.J. Thomson. Represents positive dough with negative electrons stuck inside -
Period: to
Charge of the Electron
Robert Milikan dicovered elementary charge of electron from oil drop test -
Period: to
Ruthford's Gold Foil Experiment
Had a peice of gold be hit with alpha particals. The alpha particals went through and showed Ruthford gold atoms were empty space -
Period: to
Bohr's Planetary Model
Explained atoms move in an orbit and not anywhere between. -
Period: to
Mosley's Atomic Number
Atomic number is the number of atomic charges in the atoms nucleus -
Period: to
Discovery of the proton
Ernest Ruthford figured out a proton is a positively charged sub molecule -
Period: to
Schrodinger Equation
Describes waves or probobility of waves -
Period: to
Heisenburg Unceirtainty Principal
Werner Heinsburg found you cant know both the speed and position of a partical with 100% accuracy -
Period: to
Discovery of Nuetron
Discovered by Sir James Chadwick by bomboarding beullyium with alpha particals