David.Callahan.atomichistory.fall.2009

Ancient Times

Anaximenes 610 - 546 B.C. Born in Miletus

Anaximenes believed that everthing consisted of air. He came to this conclusion by observing that air condenses into mist, rain, and other forms of precipitation. he concluded that if air does this then it will eventually condense into earth and then rocks



Democritus 460-370 B.C. Born in Abdera

Democritus theorized that everything consisted of atoms. These atoms were small, indivisible, lied in empty space, and were in constant motion. he also thought that different atoms varied in shape, size and tempature.



Aristotle 384-322 B.C. Born in Stageira, Chalcidice

Aristotle believed that everything is made from five elements, Fire, Earth, Air, Water, and Aether. he also believed that all of these elements had a natural position which, they would mve back to when mixed. He believed this is why things made of earth sink, air bubbles in water, and fire rises in air.

1700-1800

Joesph Priestly 13 March 1733 – 6 February 1804 born in: England

Priestly discovered oxygen, carbon monoxide and nitrous oxide.

A.L. Lavoisier 26 August 1743 – 8 May 1794 Born in: France

Amonst other things discovered that oxygen caused rust, pioneered stoichiometry, and discovered nitrogen. considered the father of chemistry.

A. Volta February 18, 1745 – March 5, 1827

Born In: Italy

Volta developed the Battery and discovered Methane

1800-1875

John Dalton September 6, 1766 - July 27, 1844 Born in: England

Dalton belived that all elements have different atoms and that all atoms for a single element are the same. he also belived that elements combined to form compounds and that all compounds had the same type of atoms. Dalton believed that atoms cannot be created, destroyed, or split.

Amedeo Avogadro 9 August 1776 – 9 July 1856 Born in: Italy

Avogadro was a Savant that proposed that equal volumes of gases contain the same number of molecules

J.L. Gay- Lussac 6 December 1778 – 9 May 1850 Born in: France

Lussac discovered both Boron and Iodine. He also discovered that litmus paper indictated acids and bases 1875-1900

Henri Becquerel December 15, 1852 - August 25, 1908 Born in: France

While investigatin uranium salts, Becquerel discovered Radioactivity



Wilhelm C. Roentgen March 27, 1845 - February 10, 1923 Born In: Prussia

Roentgen Discovered x-rays and because of this discovery he was awarded the first Nobel Peace Prize

Marie Curie November 7, 1867 - July 4, 1934 Born in: Warsaw Poland

Marie Curie and her husband used radioactivity to discover two new elements, Polonium and Radium,

1900-1915

Ernest Rutherford August 30, 1871 - October 19, 1937 Born in: England

Rutherford discovered Alpha, Beta, and Gamma Rays. He discovered that radiation is the decompistion of atoms. he discovered the element rutherfordium. he also helped develope the atomic bomb.



Neils Bohr October 7, 1885- November 18 1962 Born in: Copenhagen, Denmark

Bohr pioneered the electron orbital model of atomic structure. Bohr also theorized that an electron could drop from a higher energy orbit to a lower one, emitting a photo.

Robert Andrews Millikan March 22, 1868 - December 16 1953 Born In: U.S.A.

Millikan discovered the charge of electrons while teaching at the University of Chicago, by using an oil drop experiment.

1915-1950



Werner Heisenberg December 5, 1901 - February 1, 1976 Born in: Germany

Heisenberg developed the principle of uncertainty, which was the mathematic foundation of quantum mechanics, He also developed the proton-neutron atomic Model.



James Chadwick October 20, 1891 - July 24, 1974 Born in: England

In 1932 James Chadwick discovered the neutron. This discovery made it possible to create atoms heavier than Uranium in a laboratory. He was also a key piece in developing the atomic bomb.



Erwin Schrodinger 12 August 1887– 4 January 1961 Born in: Austria

Developed the Schrodinger equation which created a revolution in quantum mechanics. Also known for the Schrodinger cat thought experiment.