Which one of the following electronic configurations corresponds to an atomic ground state?

Options

A. `1s^(2)2s^(1)2p^(6)`
B. `1s^(1)2s^(2)3p^(1)`
C. `1s^(1)2s^(1)2p^(1)`
D. `1s^(2)2s^(2)2p^(1)`

Answer

To determine which electronic configuration corresponds to an atomic ground state, we need to understand the rules of electron configuration, particularly the Aufbau principle and the n + l rule.

### Step-by-Step Solution:

1. **Understand the Aufbau Principle**:
- Electrons fill atomic orbitals starting from the lowest energy level to the highest. The order of filling is determined by the increasing values of n + l, where n is the principal quantum number and l is the azimuthal quantum number.

2. **Identify the Electronic Configurations**:
- We will analyze the given configurations:
- **Option A**: 1s² 2s¹ 2p⁶
- **Option B**: 1s¹ 2s² 3p¹
- **Option C**: 1s¹ 2s¹ 2p¹

3. **Analyze Option A (1s² 2s¹ 2p⁶)**:
- This configuration has electrons in the 1s, 2s, and 2p orbitals.
- However, the 2s orbital is not fully filled before moving to the 2p orbital. This indicates that it is an excited state.

4. **Analyze Option B (1s¹ 2s² 3p¹)**:
- In this configuration, the 1s orbital is not fully filled before electrons start filling the 3p orbital. This also indicates an excited state.

5. **Analyze Option C (1s¹ 2s¹ 2p¹)**:
- Here, the 1s orbital is filled first, followed by the 2s, and then the 2p orbital. This follows the correct order of filling according to the Aufbau principle and indicates that this configuration represents a ground state.

6. **Conclusion**:
- The electronic configuration that corresponds to an atomic ground state is **Option C: 1s¹ 2s¹ 2p¹**.