Question

The ionization energy of boron is less than that of beryllium because:

• A. beryllium has a higher nuclear charge that boron
• B. beryllium has a lower nuclear charge than boron
• C. the outermost electron in boron occupies a $2p-$orbital
• D. the $2s$ and $2p$-orbitals of boron are degenerate

Answer 1

The correct option is A beryllium has a higher nuclear charge that boron

$B=5:1s^{2}2s^{2}2p^1$

$Be=4:1s^{2}2s^2$

As we can see from the electronic configuration of $Be$ it is having completely filled outermost shell which is highly stable whereas in $B$ outermost shell consists of one electron which can be removed easily for attaining a stable configuration. Hence ionization energy of B is greater than the ionization energy of $Be$.