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400
Democritus 400 b.c
Democritus proposed that there are microscopic, solid, indivisible structres that are a part of all matter. He called these stuctures atoms. -
Joseph Proust
Law of definante proportions. That all compounds contained elements with certian definate proportions -
John Dalton
Dalton proposed three ideas:
1.) All matter is composed of atoms
2.) Atoms of a given element have specific characteristics (such as chemically combining in predetermined ratios) and weights
3.) Three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules) -
Lincoln elected President
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Soccer ball invented
Hj Lindon devloped the first inflatable ball -
Thomas Edision invents the light bulb
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First Car was Invented
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Henri Becquerel
Beta-particles(electrons) are lost form the nucleus of the atom a nuetron is converted into a posetivly charged proton. Which in turn changes the atomic number of the atom. -
J.J. Thomson
Thomson discovered negativly charged electrons via cathode rays and then proposed the plum pudding model in 1904 in order to explain how he thought electrons were sparatically placed inside the atom. -
Max Planck
Planck invented the "Planck's Constant" equasion wich shows the proportional relationship between frequency and energy. He developed this equasion in order to best explain the blackbody (a body that does not reflect light because it absorbs all wavelenghts of thermal radiation) spectrum. -
Theodore Roosevelt is Inaugurated
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Robert Millikan
Was able to create an experiment that allowed him to measure the charge on an electron. He also found the mass of the electron to be 9.11 x 10^-28grams. -
Ernest Rutherford
Described that the atom had a positively charged nucleus around which negatively charded electrons circulate like planets. -
Neils Bohr
Bohr proposed the theory that electrons travel in an orbit around the atom's nucleus and that the chemical properties of the atom depend on the number of electrons in the outer most orbit. -
Quantam Mechanical Model
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World War I Begins
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World War I Ends
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Louis de Brogile
He reasoned that an electron could act like a wave. He said that the momentum (p) of an electron would equal planck's constant divided by the wavelength (l). P=h/l -
Erwin Schrodinger
Schrodinger invented the wave equation to define the atomic spectra as an eigenvalue problem. -
Werner Heisenberg
He came up with an uncertianty principle saying that electrons didn't travel in neat orbits they could have there momentum and position affected. -
James Chadwick
Chadwick discovered the existance of nutrons through atomic disintergration. -
Mcdonald's is founded
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Bouncy ball invented
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Julius Caesar was Born
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Aristotle 348 B.C.
No matter hhow many times matter was cut in half there would always be a piece of matter
