Fall.2008.MMA.Foley.Timeline

By Samantha Foley and Brendan Dickinson
 * __The History of the Atom__**


 * __450 AD and Years Prior__**

Born sometime in the 5th century
 * Leucippus**



Leucippus was born in Emlea, Abdera or Miletus. Leucippus is named as the originator of the theory that the universe has two different elements, which Leucippus called ‘the full’ or ‘solid,’ and ‘the empty’ or ‘void. The contribution to the developed atomist theory is unavailable. The reports refer to the views of Democritus alone, or to both atomists together; Epicurus seems to have denied that Leucippus even ever existed.

http://plato.stanford.edu/entries/leucippus/ http://www.aetheoraem.com/Leucippus1.jpg http://www.mlahanas.de/Greeks/LX/LeucippusWorld.jpg

460-370 BCE. -Born at Abdera, Greece (Nestos River.)
 * Democritus**



Democritus was a significant ancient greek scientist and philosopher. He made major contributions to the evolution of the atom. It was Democritus's Atomic Theory of the Universe that said atoms can not be destroyed, that they exist in a void, and they differ only in shape, position and arraigement. The tiny invisible particles he called atoms. Leucippus was the first ancient greek to first introduce the concept of the atom. Leucippus stated that atoms were the basis of all matter and Democritus expanded on that statement. Democritis and his teacher did not support this theory and developed the idea of the atom. Democritus is the more famous scientist of of the two. Most of this writings have not survived history but what he says was passed down. He claimed that atoms are the reason we percieve objects as we do. They create shape and form of all matter.

http://faculty.washington.edu/smcohen/320/Democritus.jpg http://plato.stanford.edu/entries/leucippus/

384BC-322BC
 * Aristotle**

Aristotle was born in 384 BCE. at Stagirus, a Greek colony and seaport on the coast of Thrace. Aristotle declares the existence of only four elements: fire, air, water and earth. All matter is made up of these four elements and matter had four properties: hot, cold, dry and wet.

[|http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.] http://www.ilt.columbia.edu/Publications/Projects/digitexts/aristotle/aristotle.jpg


 * __1700-1800__**

1766–1844
 * John Dalton**

John Dalton was born in a Quaker family in Cumberland, England, and was a teacher and public lecturer, beginning at the age of 12. Dalton arrived at his view of atomism by way of meteorology, in which he was seriously interested for a long time. He kept daily weather records from 1787 until his death. He proceeded to calculate atomic weights from percentage compositions of compounds, using an arbitrary system to determine the likely atomic structure of each compound.

http://www.chemheritage.org/classroom/chemach/periodic/dalton.html http://upload.wikimedia.org/wikipedia/commons/e/e9/John_Dalton.jpg

1733–1804
 * Joseph Priestley**

Priestley was educated to be a minister in the churches and he spent most of his life professional time as a teacher. He questionned the divinity of Jesus, while accepting Christianity and ironically became an early Unitarian. He was best remembered for his dis covery of oxygen and was welcomed to the United States. He was at least as well for his prodigious political and theological writings as for his scientific contributions. Priestley's first scientific work, "The History of Electricity", was encouraged by Benjamin Franklin, whom he had met in London. In preparing the publication Priestley began to perform experiments—at first to reproduce those reported in the literature but later to answer questions of his own. In the 1770s he began his most famous scientific research on the nature and properties of gases. At that time he was living next to a brewery, which provided him with carbon dioxide.

http://www.chemheritage.org/classroom/chemach/forerunners/priestley.html http://cepa.newschool.edu/het/profiles/image/priestley.jpg

1743–1794
 * Antoine Laurent Lavoisier**

Lavoisier completed a law degree because of family wishes. His real interest, however, was in science. His earliest scientific work in geology, he was elected in 1768, at the age of 25, to the Academy of Sciences, France's most elite scientific society. In 1775 Lavoisier was appointed a commissioner of the Royal Gunpowder and Saltpeter Administration and took up residence in the Paris Arsenal. He equipped a fine laboratory, which attracted young chemists from all over Europe to learn about the "Chemical Revolution" then in progress. He meanwhile succeeded in producing more and better gunpowder by increasing the supply and ensuring the purity of the constituents saltpeter (potassium nitrate), sulfur, and charcoal, as well as by improving the methods of granulating the powder.

http://www.chemheritage.org/classroom/chemach/forerunners/lavoisier.html


 * __1800-1875__

Niels Bohr** 1885-1962

Bohr attended the University of Copenhagen, winning a gold medal from the Royal Danish Academy of Sciences and Letters for his theoretical analysis of precise experiments on the vibrations of water jets as a way of finding surface tension. Bohr moved to Manchester where he worked on the theoretical implications of the nuclear model of the atom recently proposed by Rutherford and known as the Rutherford atomic model. He recognized that the various physical and chemical properties of the elements depend on the electrons moving around the nuclei of their atoms and that only the atomic weight and possible radioactive behaviour are determined by the small but massive nucleus itself. http://www.crystalinks.com/bohr.html

**William Crookes** 1833-1919  Crookes first important discovery was made in 1861 when he discovered the element thallium, with the help of spectroscopy. Crookes radiometer, in which a system of vanes, each blackened on one side and polished on the other, is set in rotation when exposed to radiant energy. However, Crookes never provided a true explanation for this.

http://en.wikipedia.org/wiki/William_Crookes  

1829-1896
 * Friedrich August Kekule von Stradonitz**

Friedrich was a German organic chemist. He was the principal founder of the theory of chemical structure. This theory begins at the idea of atomic valence, and the ability of carbon atoms to link to each other, to the determination of the bonding order of all of the atoms in a molecule. Archibald Scott Couper arrived at the idea of self-linking of carbon atoms and provided the first molecular formulas where lines symbolize bonds connecting the atoms. Kekulé's most famous work was on the structure of benzene. In 1865 Kekulé published a paper in French stating that the structure contained a six membered ring of carbon atoms with alternating single and double bonds.

http://en.wikipedia.org/wiki/Friedrich_August_Kekul