The principal quantum number of an atom is related in the

Options

A. size of the orbital
B. spin angular momentum
C. orbital angular momentum
D. orientation of the orbital in space

Explanation

To solve the question regarding the relationship of the principal quantum number (n) of an atom, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Principal Quantum Number (n)**:
- The principal quantum number (n) is a positive integer that determines the energy level and size of an electron's orbital in an atom. It can take values like 1, 2, 3, etc.

2. **Identifying the Relationship**:
- The principal quantum number is directly related to the size of the atomic orbitals. As n increases, the size of the orbital increases.

3. **Example of S-Block Elements**:
- Consider the s-block elements (Group 1) such as Lithium (Li), Sodium (Na), Potassium (K), and Rubidium (Rb).
- The outermost electronic configurations are as follows:
- Lithium: 1s² 2s¹ (n = 2)
- Sodium: 1s² 2s² 2p⁶ 3s¹ (n = 3)
- Potassium: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ (n = 4)
- Rubidium: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4p⁶ 5s¹ (n = 5)

4. **Observing the Trend**:
- As we move down the group from Lithium to Rubidium, the principal quantum number increases (2 to 5).
- Correspondingly, the size of the atom also increases (Li < Na < K < Rb).

5. **Conclusion**:
- The increase in the principal quantum number (n) leads to an increase in the size of the atomic orbitals. Therefore, we can conclude that the principal quantum number is related to the size of the orbitals.

6. **Final Answer**:
- The correct relationship is that the principal quantum number (n) is related to the size of the orbitals.