Question

Which of the following elements has the highest first ionization potential?
A. C
B. N
C. B
D. 0

Answer 1

The ionization potential of an element depends upon so many factors. Some important factors are the size of the atom, effective nuclear charge, tendency to form a stable electronic configuration, losing off a stable electronic configuration, etc.

Complete step by step answer:
In the case of carbon, boron, oxygens the electronic configuration are
1{s^2}2{s^2}2{p^2}$$$$1{s^2}2{s^2}2{p^1}, $1{s^2}2{s^2}2{p^4}$. In these configurations removal of one electron generates a stable symmetric configuration. Therefore, the energy required to remove one electron from boron requires less energy.
On the other hand, in the case of nitrogen, the electronic configuration is $1{s^2}2{s^2}2{p^3}$. This electronic conjugation has a symmetric distribution which makes it stable. Due to this stable electronic configuration, the energy required to remove the electron from its outermost shell is very high.
Therefore, nitrogen has the highest first ionization potential.

So, the correct answer is option B.

Note: From left to right of a period size decreases as nuclear charge density increases. In this viewpoint ionization enthalpy of nitrogen should be lower than oxygen. But in this case formation of stable symmetric electronic configuration overcomes the effect of size.