Lone Pair Definition in Chemistry

A lone pair is a pair of unbound outer shell electrons.
A lone pair is a pair of unbound outer shell electrons. Science Photo Library - MEHAU KULYK, Getty Images

A lone pair is an electron pair in the outermost shell of an atom that is not shared or bonded to another atom. It is also called a non-bonding pair. One way to identify a lone pair is to draw a Lewis structure. The number of lone pair electrons added to the number of bonding electrons equals the number of valence electrons of an atom. The lone pair concept is important to valence shell electron pair repulsion (VSEPR) theory, as it helps to explain the geometry of molecules.

Sources

  • Albright, T. A.; Burdett, J. K.; Whangbo, M.-H. (1985). Orbital Interactions in Chemistry. New York: Wiley. p. 102. ISBN 0471873934.
  • Ansyln, E. V.; Dougherty, D. A. (2006). Modern Physical Organic Chemistry. Sausalito, CA: University Science Books. p. 41. ISBN 978-1-891389-31-3.
  • Kumar, Anmol; Gadre, Shridhar R.; Mohan, Neetha; Suresh, Cherumuttathu H. (2014-01-06). "Lone Pairs: An Electrostatic Viewpoint". The Journal of Physical Chemistry A. 118 (2): 526–532. doi:10.1021/jp4117003