Question

Which of the following elements has a big jump from its $I{E}_1$ to $I{E}_2$?

• A. $P$
• B. $Si$
• C. $Na$
• D. $Ne$

Answer 1

The correct option is C $Na$

A big jump in ionisation energy is found when an electron is ejected from a stable inert gas configuration.
The electronic configuration of the given elements are as follows:
$P:\left[Ne\right]3s^{2}3p^3$
$Si:\left[Ne\right]3s^{2}3p^2$
$Na:\left[Ne\right]2s^1$
$Ne:\left[He\right]2s^{2}2p^6$

When an electron is ejected from $Na$, it aqcuires a noble gas configuration, $N{a}^{+}:\left[Ne\right]$. Therefore, the second electron requires a huge amount of energy for ejection. Hence, for sodium $I{E}_2>I{E}_1$.