kevin.flanigan.atomichistory.fall.2009


 * Ancient Times (450 AD and Years Prior)**

Empedocles
 * 484BC-428BC
 * Greece
 * Seperated indvisible matter into four elements; earth, water, fire, and air

Democritus
 * 460BC-370BC
 * Greece
 * Said that matter is made of small indivsible partciles with different form, position, and arragnement and called these particles atoms

Aristotle Isaac Newton Antoine Lavoisier Charles Coulomb
 * 384BC-322BC
 * Greece
 * Said that Democritus' statemnt about atoms was worthless
 * 1700-1800**
 * January 4th, 1643-March 31st, 1727
 * England
 * 1794, he proposed a mechanical universe with small solid matches in motion.
 * August 26th, 1743-May 8th, 1794
 * Paris, France
 * 1777, clarified that an element can not be broken down any further and devised a theory about the formation of compounds
 * June 14th, 1736-August 23rd, 1806
 * France
 * 1780, discovered attration and repulsion in unlike and like fluids

John Dalton Michael Faraday
 * 1800-1875**
 * September 5th, 1766-1844
 * England
 * 1803 he announced the weight of atoms and worked woth atoms throughout his life

Dmitri Mendeleev
 * September 22nd 1791-August 25th, 1867
 * England
 * 1832, Faraday split molecules with electricity,developed laws of electrolysis
 * February 8th,1834-February 2nd,1907
 * Russia
 * 1869, he arranged elements in 7 different groups with similar properties, known as the first version of periodic table

Wilhelm Roentgen Henri Becquerel JJ Thompson Marie Curie
 * 1875-1900**
 * March 27th, 1845-February 10th,1923
 * Germany
 * 1985, Roentgen worked with the cathode ray then discover x-rays
 * December 15th,1852-August 24th,1908
 * Paris, France
 * In 1896, He discovered natural radioactivity
 * December 18th,1856-August 30th, 1940
 * United Kingdom
 * 1897, He discovered that cathode rays were composed of negatively charged particles, called electrons
 * November 7th, 1867-July 4th, 1934
 * Poland
 * 1898, Marie and her husband discovered radioactivity and found the radioactive element radium in uranium

Robert Millikan Ernest Rutherford H.G.J. Moseley
 * 1900-1915**
 * March 22nd,1868-December 19th,1953
 * Morrison, Illinois
 * 1909, discovered the mass and charge of an electron in his oil drop experiment
 * August 30th,1871-October 19th, 1937
 * New Zealand
 * 1911, Discovered the negatively charged particles in the middle of an atom in his famous gold foil experiment
 * November 23rd, 1887-August 10, 1915
 * England
 * 1914, determined the charge of nuceli of most atoms, using x-ray tubes and stated the atomic number is equal to the number of protons in the nucleus

Neils Bohr Werner Heisenberg Erwin Schrodinger James Chadwick
 * 1915-1950**
 * October 7th,1885-November 18th,1962
 * Copenhagen, Denmark
 * 1922, he developed the Bohr Atomic Model
 * December 5th,1901-February 1st,1976
 * Germany
 * 1927,Described atoms by means of formula connected to the frequencies of spectral linesand proposed the Principle of Indeterminancy
 * August 12th, 1887-January 4th,1961
 * Austria-Hungary
 * In 1930, he viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom
 * October 20th, 1891-July 24th,1974
 * Cheshire, England
 * 1932, using alpha particles he discovered a nuetral charged particle with a mass close to that of a proton, otherwise known as a nuetron