Question

The following graph shows the variation of ionization energies with the atomic number in the second period $(Li-Ne)$. The value of ionization energy of $Na$ will be:

• A. Above $Ne$
• B. Below Ne but above $O$
• C. Below $Li$
• D. Between $N$ and $O$

Answer 1

The correct option is C Below $Li$

$Li$ and $Na$ are in the same group. $Na$ is a 3rd period element and is bigger than $Li$. In $Na$, the distance between the nucleus and the outer most electron is greater than Li. Thus, the outer most electron is loosely bound with the nucleus and the removal of electrons is easier as compared to $Li$.