1800-1875+clarkeson+charrette

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5 September 1766 - 27 July 1844 John Dalton was born into a poor quaker family and was educated by his father and the local school teacher. Upon his teacher's retirement, Dalton began teaching, but had to turn to farm work because of the low pay. Later, he moved to assist his cousin who ran a school. He had several publications, including a documentation of meteorological data and English grammar. He is also known for discovering and producing the first publication on color-blindness, he himself being color blind. Dalton, however, is most notably known for his atomic theory, which he formalized in 1808.

"All matter is composed of atoms Atoms cannot be made or destroyed All atoms of the same element are identical Different elements have different types of atoms Chemical reactions occur when atoms are rearranged Compounds are formed from atoms of the constituent elements."(rsc.org)

This is Dalton's Atomic Theory. It has proven very accurate, especially considering how little was known of atoms at the time. Save for a few discoveries such as isotopes, it has stood the test of time. **[|dl.clackamas.edu/ch104-04/dalton's.htm] [] ** [] [|**text bookDmitri Mendeleev**]

[|http://wpcontent.answers.com/wikipedia/commons/2/26/Дмитрий_Иванович_Менделеев_4.gif] 27 January 1834 - 20 January 1907 Dmitri Ivanovich Mendeleev was born in Siberia the youngest of at least 13 children. After his father died and his mother's glass factory burned down, his family moved to St. Petersburg where he enrolled in school. When he went to study abroad, he set up a laboratory in his apartment as opposed to studying with other chemists. In 1860, he attended the International Chemistry Congress to discuss chemical symbols and atomic masses. Mendeleev is mo st known for developing the first periodic table. It came out of his book //Osnovy Khimii.// He had noticed that elements shared qualities periodically when arranged in a table. This led to the development of the Periodic Law, which states the physical and chemical properties of elements form a pattern with increasing atomic number. Using his table, he predicted the existence of undiscovered elements and was able to predict their properties. He released his first periodic table in an article in 1869.

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Sir William Crookes
  17 July 1832 - 4 April 1919 Sir William Crookes studied chemsitry at the Royal College of Chemistry and then moved to be an assistant in meteorology at the Radcliffe observatory in Oxford. He discovered the element Thallium when investigating a residue left after the manufacture of sulphuric acid. He presented the new element at an exhibition in 1862. His studies led him to "Crooke's Tubes," in which were tubes that were used to discharge elctricity into a vacuum. []