Ice rules
In chemistry, ice rules are basic principles that govern arrangement of
John Desmond Bernal and Ralph H. Fowler who first described them in 1933.[1]
The rules state each oxygen is covalently bonded to two hydrogen atoms, and that the oxygen atom in each water molecule forms two hydrogen bonds with other water molecules, so that there is precisely one hydrogen between each pair of oxygen atoms.[2]
In other words, in ordinary
Ih ice, every oxygen is bonded to the total of four hydrogens, two of these bonds are strong and two of them are much weaker. Every hydrogen is bonded to two oxygens, strongly to one and weakly to the other. The resulting configuration is geometrically a periodic lattice. The distribution of bonds on this lattice is represented by a directed-graph (arrows) and can be either ordered or disordered. In 1935, Linus Pauling used the ice rules to calculate the residual entropy (zero temperature entropy) of ice Ih.[3] For this (and other) reasons the rules are sometimes mis-attributed and referred to as "Pauling's ice rules" (not to be confused with Pauling's rules
for ionic crystals).
A nice figure of the resulting structure can be found in Hamann.[4]
See also
References
- . Retrieved 13 April 2012.
- hdl:1811/48120.
- .
- . fig.1
External links
- Bernal–Fowler rules in Glossary of Meteorology. [1]
- Exposition by Chris Wilson and Brett Marmo. [2]
- Chaplin, Martin (15 November 2016). "The 'ice rules'". Water Structure and Science. London South Bank University, Department of Applied Sciences. Retrieved 26 March 2017.