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Aristotle (322 B.C.)
believed in four elements and that matter could always be cut in half and produce a smaller piece. No such thing as atoms. -
(Octber 1, 331 B.C.)
Alexander the Great defeats Darius III of Persia in the battle of Gaugemela. -
Democritus (460-370 B.C.)
He viewed nature as being made of tiny invisible particles called. He called these particles atoms. -
Joseph Proust
Proposed Law of Constant Composition-composition of substance never changes regardless of location or how substance was made. Atoms always have a single composition; as soon as composition changes, substance changes. -
Smallpox
Edward Jenner's smallpox vaccination is introduced. -
John Dalton
He came up with an atomic theory with spherical atoms based off measurable properties of mass. -
Louisiana Purchase
The Louisiana Purchase territory is formally transferred from France to the US for $27,000,000. -
X-rays
Wilhelm Roentgen announces his dicovery of x-rays. -
Henri Becquerel
using x-rays discovered some chemicals spontaneously decompose and give off penetrating rays. Discovered radiation. Protons and neutrons are lost from nucleus. -
J.J. Thomson
He came up with the plum pudding model which is a model of both negatively charged (electrons) and positively charged particles together in a sphere to represent an atom. Although the model was inaccurate his conclusion that the amount of electrons was equal to the atomic number was correct and that there is a positive charge to cancel the negatively charged electrons. -
Ernest Rutherford
reported the existence of alpha and beta waves in uranium radiation. Proposed atomic model with a very small, dense, positively charged nucleus surrounded by electrons. -
Spanish-American war
The Spanish-American war starts. -
Panama Canal
The US and UK sing a treaty for the Panama Canal -
Max Planck
In around 1900 he tried to make conclusions of a curiosity he had and came up with a formula that explained the quantum theory that he is known for discovering. The theory states that a quantum is equal to the frequency of the radiation times the universal constant -
Robert Millikan
determined the charge and mass of an electron using the falling-drop experiment. Found the atomic structure of electricity. -
Ernest Shackleton
Ernest Shackleton finds the magnetic South Pole. -
Neils Bohr
He came up with an explanation of and atomic structure that was the basis of the periodic table of elements. His atomic models had orbitals on them -
"Nosferatu"
"Nosferatu" premiers in Berlin. -
Louis de Broglie
discovered electrons have particle/wave duality: properties of both particles and waves. -
USSR
The Union of Socialist Soviet Republics is established. -
Werner Heisenberg
described atoms by a formula of frequencies of spectral lines. Proposed Principal of Indeterminancy, can’t know the position and velocity of a particle. -
Harlem Globetrotters
The Harlem Globetrotters play their first game in Hinckley, Illinois. -
Erwin Schrodinger
He found out that electrons were continuous clouds and introduced wave mechanics. Wave mechanics is considered to be a second formulation of the quantum theory. -
James Chadwick
He discovered a neutral atomic particle with a similar mass as a proton using alpha particles. This lead to the discovery of the neutron.
