Question

On the basis of Lanthanoid contraction, explain the following:

Nature of bonding in \[\ce{La2O3}\] and \[\ce{Lu2O3}\] .

Answer 1

As per fajan’s rule, smaller the size of ion, greater is its tendency to make covalent bonds as the positively charged cation strongly attract the negatively charged electron cloud.

On moving from \[\ce{La}\] to \[\ce{Lu}\] in the lanthanoid series, the atomic size decreases so the covalent character increases. Hence, \[\ce{La2O3}\] is ionic and \[\ce{Lu2O3}\] is covalent.