Chapter 9, Problem 9.1CYU

Check Your Understanding Why is the potential energy associated with the exclusion principle positive in Example 9.1?

To determine

To evaluate why the potential energy associated with exclusion principle is positive

Answer to Problem 9.1CYU

The potential energy associated with exclusion principle is repulsive in nature and hence it is positive.

Explanation of Solution

Introduction:

In the process of molecular formation there also exists a repelling force between the core electrons, owing to the Pauli's exclusion principle.

Oppositely charged particles are mutually attracted by a strong force of attraction between cation and anion. As the cation and anion comes closer to each other, the force of attraction becomes stronger. But when the separation among the two ions reduces beyond a certain point, a repulsive force is observed between them, owing to the exclusion principle. The energy concerned with this repulsion between core electrons is known as the potential energy associated with exclusion principle, denoted by $U_{ex}$.

This energy is repulsive in nature and by the popular convention, a preceding negative sign indicates an attractive force and a preceding positive sign indicates a repulsive force. Thus, the potential energy associated with exclusion principle is positive.

Conclusion:

The potential energy associated with exclusion principle is repulsive in nature and hence it is positive.