Atomic Theory Timeline

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Robert Boyle

1660 - 1661

Boyle demonstrated the necessity of air for combustion, for animal breathing, and for the transmission of sound.He published much influential work,including New Experiments Physio-Mechanical,Touching the Spring of the Air and its Effects and the Sceptical Chymist. In the Spring of The Air he described the inverse relationship between the volume of a gas and its pressure now known as Boyle's Law.

Joseph Priestley

1733 - 1804

Discovered oxygen. He was educated to be a minister in the churches that dissented from the church of England.

Joseph Proust

1754 - 1826

He first published his Law of Definate in 1794. This law states a compound is composed of exact proportions of elements mass regardless of how the compound was created.

John Dalton

1766 - 1794

Dalton contributed to the atomic theory,that matter is composed of the atoms of differing weights combined in simple ratio's by weight.Dalton was the first to prepare a table of relative atomic weights.

Carl Scheele

1770 - 1773

Before Priestly Scheele discovered oxygen first and called it,"fire air" because it supported combustion.

Antoine Lavoisier

1772 - 1826

Found that the mass is conserved in a chemical reaction.The total mass of the products of a chemical reaction is always the same as the total mass of the starting material consumed in the reaction.

Julius Plucker

1801 - 1829

Plucker demonstrated that analyticd geometry was capable of replacing the results of pure geometry. He replaced the point by the straight line as a fundamental element in geometry.

William Crookes

1861 - 1863

His first great discovery was that of the element thallium. He found that as the attenuation of the gas was made greater the dark spare round the negative electrode, while rays, now known as cathode rays,proceed from the electrode.

Marie and Pierre Curie

1897 - 1901

Discovered radioactive elements and created the theory of radioactivity.

J.J. Thomson

1897 - 1898

Modified Crookes tubes and found that lays inside the tube had a negative charge.

Fredrick Soddy

1898 - 1900

Worked wit Rutherford and proved that the reason for odd behavior of radioactive elements was because they decayed into other elements and created alpha, beta, and gama radiation

Jean Baptiste Perrin

1905 - 1926

Jean Perrin confirmed Einstein's ideas on Brownian motion by the empirically calculating Avogadro's Constant, conclusively proving Dalton's atomic theory.

Ernest Rutherford

1907 - 1908

Won a nobel prize in 1908 after discovering his nucleus.

Ernest Marsden

1908 - 1909

Bombarded gold atoms with alpha particles in a experiment which led to Rutherford discovery.

Robert Milliken

1908 - 1909

Performed oil-drop experiment and was able to determine the change and mass of a single electron.

Hans Geiger

1910 - 1911

Co-inventor of the Geiger counter.

James Chadwick

1928 - 1929

Discovered the neutron accounting for most of the mass in an atom.