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460
Democritus
460 B.C. - Greek philosipher who was one of the first suggested atoms exist. -
Joseph Proust
Proust composed the Law of Constant Composition, which was that the composition of the substance is always the same no matter where it was made or found. -
John Dalton
Pictured atoms as extremely small and indestructable particles with with no internal substance. This led to Dalton's atomic theory, -
J.J. Thomson
Discovered the electron and invented the cathode ray, which passes electric currents throught gases at a low pressure. -
Max Planck
Plank proposed the Plank’s constant h, explaining that the pattern of light intensity. Planck’s claim was that energy is carried in tiny units, which he named “quanta”. -
Invention of the airplane
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Ernest Rutherford
Rutherford and a few of his coworkers used massive alpha particles (atoms that have a doubly positive charge) and moved them through a thin sheet of gold foil. Most of the particles passed through the gold atoms, but a small amount deflected off at weird angles. Rutherford’s new atomic model showed that the atom is mostly empty except for the protons and neutrons inside a nucleus in the middle. -
Niels Bohr
Proposed an electron is found only in a specific orbit around the nucleus -
Period: to
World War I
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Robert Millikan
Millikan used a constructed valve and the “charge-to-mass ratio of an electron used by Thomson, he measured the electron’s mass. An electron carries one negative charge and the mass is 1/1840 of a hydrogen atom. -
Louis de Broglie
de Brogile makes a claim that since light has waves, that particles have waves as well. He claimed that moving electron particles have properties of wave. -
Erwin Schrodinger
Develops mathematical equations to describe motion of electrons in atoms. He created the electon cloud model and the quantum mechanical model. -
Werner Heisenberg
Heisenberg claims that it is impossible to know the velocity and the position of a particle at the same time. -
Period: to
The Great Depression
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James Chadwick
Discovers neutrons which have no charge and reside in the nucleus with protons. -
Period: to
World War II
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1st Helicopter
The World's first helicopter takes flight -
Penicillin
Goes into the common use for common diseases. -
Israel
Comes into first existance and a Jewish state -
The McCarthy Witchhunt
The Witchhunt hearings took place in the USA. -
SPUTNIK 1
First satelite to orbit the earth - it was a Russian spacecraft. -
NASA founded
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Muhatma Ghandi
Is arrested in India for demanding independence from England -
Aristotle
384 B.C.- Aristotle believed that the four elements of air, earth, water, and fire could always be broken down into more matter and always be divided.
