HISTORY OF THE ATOM

DEVELOPMENT OF THE ATOM

• 460 B.C Democritus developed the idea of the atoms.
• People thought his idea was worthless and no one thought about it again until 1800

JOHN DALTON

• He proposed the atomic theory in 1803.
• "All matter was composed of small indivisible particles termed atoms."
• "Atoms of a given element possess unique characteristics and weight."
• " Three types of atoms exist: elements, compounds, and complex."
• Born in the United Kingdom on September 6, 1776

J.J TOMSON

• He discovered the electron in 1897.
• He discovered the isotope in and mass spectrometry in 1912.
• In 1905 he discover the radioactivity of potassium.
• December 18, 1856 - August 30, 1940
• Cambridge, England

ERNEST RUTHERFORD

• "Father of physics"
• Rutherford model
• He discovered atoms have a nucleus.
• August 30, 1871 -October 19, 1937
• Brightwater, New Zealand

NEILS BOHR

• Showed that electrons orbit the atom.
• Bohr's model.
• Understood the quantum mechanics.
• October 7, 1885 - November 17, 1962
• Copenhagen, Denmark

IRENE CURIE

• Discovered artificial radioactivity.
• Discovered radioactive elements.
• Daughter of Marie Curie.
• September 12, 1897- March 17, 1956
• Paris, France

ROBERT MILLIKAN

• Discovered the charge of an electron.
• Din covered the mass of an electron.
• Oil Drop Experiment
• 1.60217646 × 10 -19
• March 22, 1868 - December 19, 1953

HOW ITS CHANGED OVER TIME

• New/better equipment
• More accurate information
• Better understanding

CITATIONS

• http://scienceworld.wolfram.com/biography/Dalton.html
• http://en.wikipedia.org/wiki/J._J._Thomson
• http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1908/rutherford-...
• http://www.nobelprize.org/nobel_prizes/physics/laureates/1922/bohr-bio.html
• http://www.famousscientists.org/irene-joliot-curie/

CITATIONS

• http://en.wikipedia.org/wiki/Robert_Andrews_Millikan
• http://www.timetoast.com/timelines/70073
• http://facstaff.gpc.edu/~pgore/PhysicalScience/Atoms.html