ABSTRACT
In this chapter, we will consider important structures for binary
compounds. As we learned already about the examples of elements,
the type of crystal structure or at least the preference for the
coordination number depends significantly on the type of bonding
between the NNs. Until now, we have discussed the structures of
elements, mainly with metallic and covalent bonding. In the case
of compounds, however, an important role plays the ionic bonding.
In most cases, the bonding is partially ionic and partially covalent.
It means that the atoms are partially ionized and the atomic radii
depend mainly on the degree of their ionization (oxidation state)
and also, although less, on the coordination number. The two types
of ions in a binary compound have in general different radii and
its crystal structure depends strongly on the cation to anion radius
ratio.
