The Changing Nature of Science
Part 1
Evolution of the Atomic Theory
Ancient Greece
•Democritus
(c.470-c.380) suggested “just like the beach looks like a single substance so might all the matter be made up of tiny granules of matter”
•He named those granules atoms (“atomos”- indivisible)
•His ideas were forgotten for the next 2000 years
(McPhee, 2010)
The scientists of the 19th centuries renewed their interest in the Atomic Theory
•John Dalton suggested that all matter was composed of small particles - atoms, each element had a different atom and a different atomic weight, theorized that atoms could not be created or destroyed in chemical reactions (1804)
•In his attempt to classify the elements by principles, Dmitri
Mendeleev arranged the elements by their atomic weight, discovering the existence of periodicity of the atoms (1869)
•J.J. Thomson discovered electrons through his cathode ray experiment and proved that atoms were divisible(1897)
(McPhee, 2010), ("A brief history," 2005)
20th century concepts and discoveries
•Earnest Rutherford discovered that there was a small, dense positively charged nucleus, predicted the existence of neutrons, stated that electrons move rapidly in the empty space around the nucleus
(1909-11)
•In continuation of his experiments J.J. Thompson determined that all particles had charges that were multiples of the same number
•In 1913 Robert Millikan accurately determined the mass of election
•Chadwick discovered the previously unknown part of an atom - the neutron, his discovery made it possible to create new elements (heavier than Uranium) in the laboratory (1931)
("A brief history," 2005)
Part 2
1980 Eruption of
Mount St.Helens
The World in 1980:
•The Global Positioning System time began at 00:00 UTC (January 6)
•The president of Sicily was killed by the Mafia (January 6)
•The 1980 Winter Olympics opened in Lake Placid, New York (February 13)
•The
References: A brief history of atomic theory development. (2005). Retrieved from http:/ McPhee, I. (2010). Physics everyday science at the speed of light. New York: Metro Books. Peebles, L. (2010). 11 surprising natural lessons from mount st. helens. Volcano watch. (2005, May 19). Retrieved from http:/ /hvo.wr.usgs.gov/