Atoms and Molecules - Bonding |
Covalent bonding is a specific type of bond between two atoms. Lots of molecules are held together by covalent bonding, such as water. This page will describe the history, and definition of covalent bonding, and also include some useful videos and animations.
Gilbert Lewis first described covalent bonding using what is now known as Lewis diagrams, where dots representing electrons surround the nucleus, symbolized by the element symbol. Pairs of electrons located between atoms represent covalent bonds. Multiple pairs represent multiple bonds, such as double and triple bonds.
Lewis was born on October 23, 1875, in Weymouth, Massachusettes. He attained his Ph.D. at Harvard. He studied under physical chemist Wilhelm Ostwald and then physicist Walther Nernst. Because of this physics influence, he was very interested in how electrons move around the nucleus of an atom. Lewis also taught at Harvard, Massachusettes Institute of Technology (MIT), and the College of Chemistry at the University of California, Berkeley. In 1916 he published a paper "The Atom and the Molecule". This paper also included what became known as Lewis dot structures, which he used to introduce the idea of a covalent bond, though the term was not used.
Irving Langmuir was the first known person to use the term covalence in Journal of the American Chemical Society. He defined it as "the number of pairs of electrons which a given atom shares with its neighbors."
Covalent bonding is when two atoms share a pair of valence electrons to form a bond. When this happens, each atom experiences a noble gas like stability. Hydrogen gas is a simple example. Each hydrogen atom contributes one electron, and therefore can utilize both electrons. This gives each hydrogen stability similiar to the noble gas helium. Another example would be the diatomic gas chlorine. Notice in both of these cases, there is equal contribution and sharing of electrons by both atoms.
The word covalent is comprised of two root words, co- and valent, or valence. Co- means with, or jointly, and -valent refers to the valence electrons in an atom. Therefore, covalent bonding is when two atoms share a pair of valence electrons to form a bond.
Covalent bonding is when two atoms are held together by sharing electrons. It can be thought of as a rubber band strip, with two objects at either end. The bond can stretch, but will eventually break if stretched far enough.
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Instructional video.
Instructional Video.
http://www.woodrow.org/teachers/ci/1992/Lewis.html
Edsall, J. T. (November 1974). "Some notes and queries on the development of bioenergetics. Notes on some "founding fathers" of physical chemistry: J. Willard Gibbs, Wilhelm Ostwald, Walther Nernst, Gilbert Newton Lewis". Mol. Cell. Biochem. 5 (1–2): 103–12.
Langmuir, Irving (1919-06-01). "The Arrangement of Electrons in Atoms and Molecules". Journal of the American Chemical Society 41 (6): 868–934.
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html
http://chemistry.about.com/od/chemistryglossary/a/covalentbonddef.htm
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