Question

Ionization potential increases across a period from left to right because the

• A. (a) atomic radius increases and nuclear charge increases
• B. (b) atomic radius decreases and nuclear charge decreases
• C. (c) atomic radius increases and nuclear charge decreases
• D. (d) atomic radius decreases and nuclear charge increases

Answer 1

The correct option is D

(d) atomic radius decreases and nuclear charge increases

Part 1: Explanation for Correct answer

Option (d) atomic radius decreases and nuclear charge increases

1. When we move across the period from left to right, the ionization potential increases.
2. This happens because as we go from left to right the atomic radius decreases.
3. And the effective nuclear charge increases, which results in the nucleus pulling the electrons closer to itself.

Part 2: Explanation for incorrect answer

Option (a) atomic radius increases and nuclear charge increases

1. Atomic radius does not increase when we go from left to right, it decreases.
2. Hence this option is incorrect.

Option (b) atomic radius decreases and nuclear charge decreases

1. As the atomic radius decreases the effective nuclear charge increases, not decreases.
2. Hence this option is incorrect

Option (c) atomic radius increases and nuclear charge decreases

1. The effective nuclear charge increases due to the fact that the atomic radius decreases on going from left to right across a period.
2. Hence this option is not correct.

Hence, the ionization potential increases across a period from left to right because option (d) atomic radius decreases and nuclear charge increases.