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340
Aristotle
In his lifetime (384 - 322 B.C.), he believed matter was infinitely divisible, and he didn’t believe Democritus’ idea of the existence of an atom. -
500
Democritus
Around 500 B.C. Democritus proposed a theory that everything is composed of atoms, which are physically, indivisible to the human eye. Also, between atoms lies empty space and atoms are indestructible, in motion, and that there are an infinite number of them. -
Oct 12, 1492
Christopher Columbus
He discoveres the "New World." -
Signing of the Declaration of Independence
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Joseph Proust
Proust published his law of definite proportions which said that when compounds are broken up into their respective parts, they have the same weight as their elements. This led to Dalton’s atomic theory. -
John Dalton Proposes Atomic Theory
In 1803 John Dalton proposes the Atomic Theory, but did not publish his ideas until 1805. -
Confederate Army surrenders to Union Army
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Creation of Basketball
James Naismith invented and named the game of basketball in 1891. -
Henri Becquerel
He discovers natural radioactivity on accident. -
J.J. Thomson
In 1897, J.J. Thomson discovered the negatively charged electron. -
Max Planck
Planck proposed Planck's constant h, 6.63 × 10-34, which is in the equation for light intensity emitted from a particle at any given frequency. He also won the Nobel Prize for Chemistry for his contributions toward his extrordinary findings. -
J.J. Thomson and the "Plum Pudding" Model
Thomson created the "Plum Pudding" atom model in 1904, which was filled with positively charged particles and a certain number of electrons in a sphere shape. -
Robert Millikan
His oil drop experiments measured an electron's charge. Through his work he silences doubts on the atomic and kinetic theories of matter. -
Ernest Rutherford
He presents the Rutherford Model of the Atom. He was also the first to come up with the nuclear theory of the atom. -
Niels Bohr
Bohr contributed to the structure of the atom by creating the Bohr model of the atom, the theory that electrons travel in discrete orbits around the atom's nucleus. Also he proposed the shell model of the atom, where the chemical properties of an element are determined by the electrons in the outermost orbit. -
World War I Begins
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Invention of Bra
Mary Phelps Jacob puts an end to the painfulness of corsets by inventing a simple bra. -
Louis de Broglie
He suggested that the electron has a wavelength. -
Werner Heisenberg
He developed quantum mechanics which is a way to calculate the behavior of the subatomic particles. In 1927, he discovered the uncertainty principle. -
Erwin Schrodinger
Schrodinger publishes his work on his now well-known wave theory, stating that "a confined particle with known energy and momentum functions could be described with a certain wave function." This means that the frequencies of the light emitted depended on the structure of an atom that the electron was bound to. -
Invention of Scotch Tape
Richard Drew invents Scotch Tape -
James Chadwick
Chadwick discovers the non-electric charged neutron. This was a huge accomplishment because then, the neutron was added to the structure of the atom. -
D-Day
Allied Troops invade the beaches of Normandy in World War II -
Invention of Bar Codes
Joseph Woodland first issues bar codes in a store -
"I Have A Dream"
Martin Luther King Jr. gives his speech "I Have A Dream" on the steps of the Lincoln Memorial. -
General Motors
General Motors creates the first set of airbags in a Chevrolet car
