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Jan 1, 1000
Democritus of Adbera
Democritus determned that atoms are indvisible. He was also the first to identify the possibility of an atom and also that it is the smallest piece of matter (5th century B.C.) -
Jan 1, 1000
Aristotle
(mid 300s B.C.) Aristotle discovered the four elements, earth, fire, air, and water. He believed in reasoning instead of scientific experiments and dismissed Democritus' atom idea asm"worthless". -
Antoine Lavoisier
Lavoisier came up with the Law of Conservation which states matter cannot be destroyed or created. He discoverred that matter can be rearranged but never disappear. -
John Dalton
The main points of Dalton's atomic theory were that elements are made of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed. -
Solid Sphere Model
created by John Dalton -
Joseph John Thomson
Thomp\son discovered the electron, and described nature of cathode rays. He also is responsible for the plum pudding model of an atom -
Robert Millikan
Millikan measured the charge of an electron and received a Nobel prize for doing so. He also completed the oil drop experiment with Thomson. -
Max Planck
Planck stated that atoms can emit "quanta". Einstein also used his work to study photons. -
Marie Curie
Marie Curie dicovered the radioactiv elements polonium and radium. She also discovered that elements may change into anotherelement naturally unnstable nucleus. -
Henri Becquerel
Becquerel discovered radioactivity however he did not pursue it. Furthermore, he discovered that radioactivity did not only come from the sun, which lead him to the discovery of spontneous radioactivity. -
Plum Pudding Model
Created by J.J. Thomson -
Albert Einstein
Einsteins atomic theory states that any liquid is made of molecules. These molecules are in random motion. Einstein realized that these random molecules will produce statistical fluctuations. -
Ernest Rutherford
Ernest Rutherford found the gold foil experiment, discovered that atoms have a small positive nucleus and he also predicted the existence of neutrons. -
Niels Bohr
Bohr developed the planetary model of an atom and discovered that electrons travel in specified energy levels. He is aso responsible for the spectrum lines produced when electrons move. -
planetary model
created by Bohr and Rutherford -
Louis deBroglie
deBroglie discoveredd that electrons have properties of both waves and particles. The groups of waves are named after him. -
electron cloud model
created by schrodinger -
Erwin Schrodinger
Schrodinger showed mathematically that waves can be used to describe electrons in atoms. He is also accountable for determining probability location of electrons in atoms. -
quantum mechanical model
bohr and shrodinger created it -
Werner Heisenberg
Heisenberg developed the "uncerainty principle". He also observed that it is impossible to determine the position and the momentum of a particle at the same time. Werner also is respoonsible for the quantum mechanical model. -
James Chadwick
Chadwick helped with the developement of the nuclear model. He also was the first to discover the neutron. -
Otto Hahn
In 1938, Hahn, Meitner, and Strassman became the first to recognize uranium atom can be split when bombarded by neutrons. It was generally expected that elements close in atomic number, elements with higher atomic numbers than uranium will be produced. -
Glen T. Seaborg
Seaborg called for the greatest change to be made to the periodic table of elements. He also formulated the actninide concept of heavy element electronic structure which predicted that the actninids will form a transition series analogous to the rare earth series of lanthanide elements. -
Sources
www.lbl.gov and wikipedia are the only sources i used for the whole project.
