Making the most of valency

By Peter Nelson2010-05-01T00:00:00

Source: Thomas Hollyman/SPL

Teachers are encouraged to use valency as a way of rationalising the atomic composition of a large number of compounds

In Short

Modern treatment of valency, showing how simple and effective it is
If students know the formulae of a few well-known compounds - H₂O, CO₂etc - they can work out most of the important valencies

Chemical bonding

When the theory of valency was devised, chemists thought that all compounds were molecular. We now know that many are non-molecular, ie they comprise a large number of atoms bound together in a continuous framework.¹ The theory can, however, be adapted to include non-molecular compounds. In this article I shall distinguish the two types by writing the formulae of non-molecular compounds as exemplified by (NaCl)∞.

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