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400
Democritus
Claimed that the world was made up of an "infinite number of atoms" that are all different shapes and substances -
Isaac Newton
Proposed that there was a mechanical universe with tiny solid masses in motion -
John Dalton
Believed that there were small spherical atoms in motion based on measurable properties in mass -
Micheal Faraday
" Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism. those words came from this website "http://atomictimeline.net/index.php -
J. Plucker
built one of the first gas discharge tubes -
Dmitri mendlevee
Created the periodic law based on "were periodic functions of the their atomic weights' -
James Clerk Maxwell
propsed that the electric and magnetic feild fills void -
Sir William Crookes
"Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass. " those words came from this website http://atomictimeline.net/index.php -
E. Goldstein
used canal rays which had electrical and magnetic properties opposite of an electron -
G.J. Stoney
Proposed that electrical charges were made up of dicrete particles that were charged negatively that were called electrons -
R.A. Millican
"Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron. "http://atomictimeline.net/index.php -
Ernest Rutherford
Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil . He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus. http://atomictimeline.net/index.php -
Niels Bohr
he made an explantion of the layout of atomic structure that underlies the regularaties of the perdiodic table -
de Broglie
discovered that electrons had dual nature to both wave particles and wave duality, this theory was supported by Einstein -
Heisenburg
Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle. http://atomictimeline.net/index.php -
Paul Dirac
Proposed anti-particles . Anderson discovered the anti-electron (positron) in 1932 and Segre/Chamberlain detected the anti-proton in 1955 http://atomictimeline.net/index.php -
Enrico Fermi
Made the first controlled chain reaction by releasing energy in the nucleus
