ATOMIC HISTORY

DEMOCRITUS

• Born: 460 in Greece
• Atomic Theory
• Hypothesized that all matter is composed of tiny units (Atoms)
• Died: 370 BCE in Greece

JOHN DALTON

• Born: September 6, 1766 in Eaglesfield, England. Died: July 27, 1884 in Manchester, England
• Atomic Theory (Early 1800s)
• All matter is made of atoms
• All atoms of a given element are identical in mass and properties
• Compounds are formed by a combination of two or more different elements

DMITRI MENDELEEV

• Born: February 8, 1834 in Siberia, Russia
• Periodic Table (Late 1860s)
• Predicted the existence and properties of new chemical elements
• Died: February 2, 1907 in St. Petersburg, Russia

J.J. THOMSON

• Born: December 18, 1856 in Manchester, United Kingdom
• Electron (1897)
• Discovered the electron in a series of experiments
• Designed to study the nature of electric discharge in a high-vacuum cathode-ray tube
• Died: August 30, 1940

ALBERT EINSTEIN

• Born: March 14, 1879 inWürttemburg, Germany
• Theory of Relativity (1905)
• Time and length are not as absolute as everyday experience
• Mass and Energy are equal
• Died: April 18, 1955 in Princeton, New Jersey

ERNEST RUTHERFORD

• Born: 1871
• Alpha and Beta Rays (1907)
• He discovered alpha and beta rays
• Did experiments in his lab that showed alpha particles are fired into gas atoms
• Died: 1937

NIELS BOHR

• Born: October 5,1885
• Discovered that electrons travel in separate orbits around the nucleus (1913)
• The number of electrons in the outer orbit determines the properties of an element
• Died: November 18, 1962

JAMES CHADWICK

• Born: October 20,1891
• Neutron (1932)
• Neutral particle with a mass about that of a proton
• Died: July24, 1974

LISE MEITNER AND OTTO HAN

• Born: 1878, 1879
• Uranium atom(1938)
• Experiments in the lab when Meitner began to get strange results form the Uranium atom
• Died: 1968

JULIUS ROBERT OPPENHEIMER

• Born: April 22, 1904
• Mahattan Project (1945)
• Manhattan Project, a U.S harness nuclear energy for military purposes.
• Died February 18, 1967