Chapter 29, Problem 5P

(a)

To determine

To Explain: The reason due to which molecule ${\text{He}}_{\text{2}}$ is not formed.

Explanation of Solution

Introduction:

In the neutral helium atom, there are two electrons in ground state, where $n=1,l=1\text{and}{m}_l=0$ . These electrons have opposite spin.

The electron from one of the atoms having the same quantum number as one of the electrons in another atom are required for the covalent bond formation. But it is not allowed on the bases of exclusion principle. Therefore, electrons cannot be shared.

Conclusion:

Thus, the molecule ${\text{He}}_{\text{2}}$ is not formed.

(b)

To determine

To Explain: The reason for the formation of ${\text{He}}_2^{+}$ .

Explanation of Solution

Introduction:

In the neutral helium atom, there are two electrons in ground state, where $n=1,l=1\text{and}{m}_l=0$ . These electrons have opposite spin.

The ${\text{He}}_2^{+}$ has lone electrons due to which it has net spin value as $S=+\frac{1}{2}$ and $S=-\frac{1}{2}$ . The existence of net spin values proves that helium ion can be formed.

Conclusion:

Thus, helium ion is formed.