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460
Democritus
-Democritus was born in 460 BC and died in 370 BC
- His was the first theory of the atom
-He proposed the theory that everything was made up of atoms
-He believed that were infinite number of atoms and that there were also different kinds of atoms
-He came up with the theory that atoms are indestructable
-Atoms are always in motion and are continually moving
-There are lots of atoms and they differ in shape and size -
First Fleet arrives in Australia
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John Dalton
-Proposed that elements are made up of atoms
-That atoms had measureable properties of mass
-Proved that in chemical reactions atoms can be combined, seperated or rearranged
-First person to discover compounds, discovered that compounds are formed by a chemical reaction
-Believed that atoms could not be subdivided, created or destroyed -
Period: to
Crimean War
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JJ Thomson
-Proposed the plum pudding model
-An atom was a solid sphere that was neutrally balanced with electrons embedded in it
-There are the same number of protons and neutrons
-Protons had a larger mass
-Was the first to discover electrons
-Discovered sub atomic particles and that isotopes are radioactive -
Ernest Rutherford
-Proposed that atoms were made up of mostly empty space
-Through an experiment where he used radiation he discovered that every atom had a nucleus
-Found that electrons move in circular orbits around the nucleus
-Discovered that there was and electrostatic force between the nucleus and electrons, which meant that not all the particles in the atom were positively charged
-Discovered that the nucleus contained all the mass of the atom and it also contianed the positive charge of the atom -
Niels Bohr
-Found that electrons could move between energy levels
-Electrons do orbit the nucleus but they orbit it in shells
-Discovered that the number of electrons in the valence shell explains the chemical and physical properties of an element
-Used the quantum theory that energy is transferred only in certain well defined quantities to explain his own theory. -
Period: to
World War 1
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Erwin Schrodinger
-Discovered that a valence shell was neither empty nor full
-He developed the Stark effect with Leinsberg
-Solved the quantum harmonic oscillator
-The exact path of an electron cannot be determined
-Introduced 'wave mechanics' as a mathematical equation of atoms -
James Chadwick
-Discovered the prescence of the neutron
-Won a noble prize for physics
-Found that neutrons had almost the same mass as protons
-He bombarded beryllium with a alpha particles and discovered that the particles of the rays were not delfected by a magnatic or electric field which indicated that some particles carried no charge -
Atomic Bombing of Japan
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Space travel to the moon
the americans were the first people to land on the moon -
Chernobyl Nuclear Accident
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Hubble Telescopeis Launched
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Opening of the Large Hadron Collider.
