The first member of each group of representative elements (i.e., s and p-block elements) shows anomalous behaviour. Illustrate with two examples.
Anomalous Properties of Second Period Elements: The anomalous behaviour is because of their small size, large charge/radius ratio, high electronegativity, and non-availability of d-orbitals in their valence shell.
example:
1. Compounds of lithium have significant covalent character. whereas compounds of other alkali metals are predominantly ionic.
2. In p-block elements, the first member of each group has four orbitals: one 2s-orbital and three 2p-orbitals, which are their valence shell. So, these elements show a maximum covalency of four, while other members of the same group or different groups show a maximum covalency beyond four due to the availability of vacant d-orbitals.