The correct electronic configuration of lanthanum is

Options

A. `[Xe]5d^(1)6s^(2)`
B. `[Xe]4d^(1)5s^(2)`
C. `[Xe]4f^(1)5s^(2)`
D. `[Xe]5f^(1)6s^(2)`

Answer

To determine the correct electronic configuration of lanthanum (La), we can follow these steps:

### Step 1: Identify the Atomic Number
Lanthanum has an atomic number of 57. This means it has 57 electrons.

### Step 2: Write the Electron Configuration
We will fill the electron orbitals according to the Aufbau principle, Hund's rule, and the Pauli exclusion principle. The order of filling is as follows:
1. 1s
2. 2s
3. 2p
4. 3s
5. 3p
6. 4s
7. 3d
8. 4p
9. 5s
10. 4d
11. 5p
12. 6s
13. 4f
14. 5d
15. 6p

### Step 3: Fill the Orbitals
Now we fill the orbitals with electrons:
- 1s² (2 electrons)
- 2s² (2 electrons)
- 2p⁶ (6 electrons)
- 3s² (2 electrons)
- 3p⁶ (6 electrons)
- 4s² (2 electrons)
- 3d¹⁰ (10 electrons)
- 4p⁶ (6 electrons)
- 5s² (2 electrons)
- 4d¹⁰ (10 electrons)
- 5p⁶ (6 electrons)
- 6s² (2 electrons)
- 4f¹ (1 electron)

### Step 4: Combine the Electron Configuration
After filling all the orbitals, we find that the total number of electrons is 57. The correct electronic configuration for lanthanum is:
\[ \text{[Xe]} 6s^2 5d^1 \]

### Conclusion
Thus, the correct electronic configuration of lanthanum is:
\[ \text{[Xe]} 5d^1 6s^2 \]