Question

the first ionization enthalpy $\left({\Delta }_i\text{H}\right)$ values of the third period elements, Na, Mg and Si are respectively 496, 737 and 786 kJ mol${}^{-1}$. Predict whether the first ${\Delta }_{i}H$ value for Al will be more close to 575 or 760 kJ mol${}^{-1}$? Justify your answer.

Answer 1

Since $IE=Na<Al<Mg<Si$ $;$

Hence ${}^{\prime }M{g}^{\prime }$ has ${3s}^2$ configuration $($fullfilled$)$

so has more ionisation than its neighbour only$.$