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Period: to
Scientific Discoveries
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John Dalton
LAW OF MULTIPLE PROPORTIONS: Whenever two elements form more than one compound, the different masses of one element combined with the same masses of the other element are in a ratio of small whole numbers.
ATOMIC THEORY: all elements are made of atoms, atoms can mix together or chemically combine to form compounds, atoms of the same element are identical, chemical reactions occur with the gain, loss, orrearrangement of atoms, chemical reactions don't lead to chang of atom into another element. -
Lewis and Clark
Lewis and Clark expedition heads out toward the Pacific Ocean to explore the west and the Louisiana Purchase. -
J.J. Thomson
Discovered the electron and came up with the raisin bread theory that stated that, like raisin bread, negatively charged electrons were sprinkled inside of atoms of positively charged protons, the bread. -
Spanish American War
Spanish American war begins between Spain and the United States -
Max Planck
PLANCK'S CONSTANT(h): 6.626x10^-34
(proportion of energy and frequency of electromagnetic waves)
E=hv -
Hantaro Nagaoka
Developed an early yet incorrect planetary model of the stom based off the rings of Saturn, with electrons forming the rings and a positively charged sphere of large mass in the center. -
Robert A Millikan
Discovered the negative charge carried by electrons using his oil drop method and proved that the mass and charge of an electron is a constant. -
Lord Ernest Rutherford
GOLD FOIL EXPERIMENT: This tested J.J. Thomson's plum pudding model. He shot energetic alpha particles at foil and measured the angle of the particles as the came out the other end. Because they scattered and deflected, he concluded that atoms contained a nucleus. -
Titanic
The Titanic ship sinks in the middle of the Atlantic Ocean. -
Niels Bohr
BOHR MODEL: Bohr theorized that electrons were located on different energy levels that were fixed at different distances from the nucleus. Levels that were farther away had electrons that had absorbed more energy. -
Treaty of Versailles
The Treaty of Versailles ends WWI which began in 1914. -
Erwin Schrodinger
Studied the theory of Louis de Broglie and published his quantum mechanical model, or wave equation. It is based on the quantum theory which states that matter has properties associated with waves. (published first ideas in 1917) -
Louis de Broglie
WAVE PARTICLE DUALITY OF NATURE: all matter, not just light, has wave properties.
(all particles , like the electron, must be transported by the wave into which it is incorperated) -
Werner Heisenberg
PRINCIPAL OF UNCERTAINTY: states that it is impossible to know the position and momentum of a particle at the same time, becasue while you accurately measure the particles position, the measurement of the momentum becomes less accurate, and vise versa. (1925 published theory of quantum mechanics) -
Sir James Chadwick
Discovered the neutron. He observed that if exposed to an assault of alpha pparticles, beryllium released unknown radiation that ejected protons fromt he nuclei of substances, and he could therefore split the nucleus this way. Refuted hypothesis that the extra mass in the nucleus was protons paired with neutrons. -
Dust Bowl
A great drought called the Dust Bowl sweaps over the United States.
