Question

Explain the diagonal relationship of Li of first group and Mg of second group.

Answer 1

The diagonal relationship between 2nd and 3rd period of the periodic table between the elements such as Li and Mg, Be and Al, B and Si is because on moving from left to right in a periodic table certain properties change and neutralize the effect of the change in properties on going down the group so as to form a relationship with them.

Also, the number of shells remain same , effective nuclear charge increases and hence size decreases, and covalent nature increases due to less electronegativity difference.

Answer 2

size decrease

hope this will help you