In chemistry, ice rules are basic principles that govern arrangement of

atom Atoms are the basic particles of the chemical elements. An atom consists of a atomic nucleus, nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished fr ...

s in water

ice Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

. They are also known as Bernal–Fowler rules, after British physicists John Desmond Bernal and

Ralph H. Fowler Sir Ralph Howard Fowler (17 January 1889 – 28 July 1944) was an English physicist, physical chemist, and astronomer. Education Ralph H. Fowler was born at Roydon, Essex, Roydon, Essex, on 17 January 1889 to Howard Fowler, from Burnham-on-Sea, ...

who first described them in 1933. The rules state each

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

is covalently bonded to two

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

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. In other words, in ordinary I_h 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 Linus Carl Pauling ( ; February 28, 1901August 19, 1994) was an American chemist and peace activist. He published more than 1,200 papers and books, of which about 850 dealt with scientific topics. ''New Scientist'' called him one of the 20 gre ...

used the ice rules to calculate the residual entropy (zero temperature entropy) of ice I_h. 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 Pauling's rules are five rules published by Linus Pauling in 1929 for predicting and rationalizing the crystal structures of ionic compounds. First rule: the radius ratio rule For typical ionic solids, the cations are smaller than the ani ...

for ionic crystals). A nice figure of the resulting structure can be found in Hamann.

References

External links

* Bernal–Fowler rules in Glossary of Meteorology

* Exposition by Chris Wilson and Brett Marmo

* {{DEFAULTSORT:Ice Rules Water ice

See also

References

External links