Question

Arrange the following in the given order : Increasing first ionization energy : $Mg,Al,Si,Na$

• A. $Na<Al<Mg<Si$
• B. $Si<Mg<Al<Na$
• C. $Na<Mg<Al<Si$
• D. None of these

Answer 1

Answer: (A)

$Na<Al<Mg<Si$

The increasing order of first ionization energy is
$Na<Al<Mg<Si$
From left to right, the ionization energy increases. But in magnesium, stable configuration is present. Therefore, its ionization energy is greater than that of aluminium.
$Mg:I{s}^{2}2s^{2}2p^{6}3s^2$