Q.Mention any two anomalous properties of second period elements.

Step 1. Second-period elements such as Li and Be form more covalent compounds than the rest of their respective groups (which predominantly form ionic compounds) -- e.g. lithium salts show more covalent character than sodium or potassium salts.

Step 2. Second-period elements have only the 2s and 2p orbitals available in their valence shell (no d orbitals), capping their maximum covalence at 4; later members of the same groups have available d orbitals and so can exceed this. For example, boron forms only $BF_4^-$ (covalence 4) while alumin …

Recall the two headline anomalies of Section 3.6.1: extra covalent character, and the covalence-4 …

• Confusing this with the diagonal relationship (a separate, though related, anomaly) instead of the specific 'first member …