Question
Amongst the elements with following electronic configurations, which one may have the highest ionisation energy?
A.
$$\left[ {Ne} \right]3{s^2}3{p^3}$$
B.
$$\left[ {Ne} \right]3{s^2}3{p^2}$$
C.
$$\left[ {Ar} \right]3{d^{10}},4{s^2}4{p^3}$$
D.
$$\left[ {Ne} \right]3{s^2}3{p^1}$$
Answer :
$$\left[ {Ne} \right]3{s^2}3{p^3}$$
Solution :
Key Idea Across a period, increasing nuclear charge outweighs the shielding, hence the outermost electrons are held more and more tightly and ionisation energy. increases across a period while as we move down a group increase in shielding outweighs the increasing nuclear charge and the removal of the outermost electron required less energy down a group.
| Electronic configuration |
Group |
| $$\left[ {Ne} \right]3{s^2}3{p^3}$$ |
$${\text{V}}$$ |
| $$\left[ {Ne} \right]3{s^2}3{p^2}$$ |
$${\text{IV}}$$ |
| $$\left[ {Ar} \right]3{d^{10}},4{s^2}4{p^3}$$ |
$${\text{V}}$$ |
| $$\left[ {Ne} \right]3{s^2}3{p^1}$$ |
$${\text{III}}$$ |
Since, ionisation energy increases in a period and decreases in a group, $$\left[ {Ne} \right]3{s^2}3{p^3}$$ configuration has the highest ionisation energy among the given elements.