John Dalton

Bobbi Moorer, Mora Downs, Taylor Nelson, and Michaela Kirck

Big image
John Dalton was an English chemist who provided beginnings of the development of a scientific atomic theory, creating the development of chemistry as a separated science. In Dalton's work he used simple equipment and had been accused of being "a very coarse experimenter." Although he had a gift for reasoning and drawing correct conclusions from imperfect experiments his success was primarily to simple persistence.

Early life

Dalton was born into a family of devout Quakers in a small village in the Lakes District of northwest England. He was largely self-educated and, and learned most of his math and science by teaching others. He studied mathematics at a local school until age 11, then started his own school at the age of 12. At the age of 15 he started teaching with his brother Jonathan. John Dalton described his own color blindness in 1794. In common with his brother, he was affected by red-green colorblindness. He postulated that the shortage in color perception was caused by discoloration by the liquid medium of the eyeball called aqueous humour. According to his research he believed that the aqueous humour was bluish and therefore filtered out all of the colors. His observations and writings formed the expression "Daltonism", which is now a common word for colorblindness.

The Atomic Theory

John Dalton is most known for creating the first "modern" atomic theory. He developed his theory as a way of trying to answer certain questions about the atmosphere. Dalton believed that the atmosphere was a physical mixture based on his belief that water vapor could not be combined chemically with the gases in the air. He believed the atoms contained a shield of heat around them. The theory was published in New System of Chemical Philosophy in 1808. “In his 1808 book, A New System of Chemical Philosophy, Dalton outlined five fundamental postulates about atoms. He postulated that all matter consists of tiny, indivisible particles, which he called atoms. All atoms of a particular element are exactly alike, but atoms of different elements are different. All atoms are unchangeable. Atoms of elements combine to form "compound atoms" (i.e., molecules) of compounds. Finally, Dalton postulated that in chemical reactions, atoms are neither created nor destroyed, but are only rearranged.” His theory was not necessarily new. Greek philosopher, Democritus of Abdera had proposed a similar theory of matter in the fourth century B.C. His ideas filtered in and out of the writings of scientists for 22 centuries. Dalton was the first person to express the ideas in modern form.

Dalton's Atomic Model

Main Points

  1. Elements are made of extremely small particles called atoms.
  2. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
  3. Atoms cannot be subdivided, created, or destroyed.
  4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
  5. In chemical reactions, atoms are combined, separated, or rearranged.

Bibliography

"John Dalton." Encyclopedia of World Biography. Detroit: Gale, 1998. Biography in Context. Web. 21 Nov. 2014.


"John Dalton." World of Chemistry. Gale, 2006. Biography in Context. Web. 21 Nov. 2014.


"Atomic theory." World of Biology. Gale, 2006. Biography in Context. Web. 21 Nov. 2014.


"John Dalton Proposes His Atomic Theory and Lays the Foundation of Modern Chemistry." Science and Its Times. Ed. Neil Schlager and Josh Lauer. Vol. 5. Detroit: Gale, 2001. Biography in Context. Web. 21 Nov. 2014.


"John Dalton." World of Scientific Discovery. Gale, 2006. Biography in Context. Web. 24 Nov. 2014.


Childs, Peter E. "Dalton, John." Chemistry: Foundations and Applications. Ed. J. J. Lagowski. Vol. 2. New York: Macmillan Reference USA, 2004. 1-3. Gale Virtual Reference Library. Web. 24 Nov. 2014


"John Dalton." Wikipedia. Wikipedia. Web. 23 Nov. 2014. <http://en.wikipedia.org/wiki/

John_Dalton>.