In a period, on moving from left to right, the ionic radius decreases. Hence, $N a^{+}>M g^{2+}>A l^{3+}$ and $L i^{+}>B e^{2+}$
In a group, on moving down from top to bottom, the ionic radius increases. Hence, $N a^{+}>L i^{+}$ and $M g^{2+}>B e^{2+}$
$M - 1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^{10}}4{s^1}$ આ તત્વ કયા જૂથનું હશે?