Which of these is the correct electronic configuration of Platinum (At. Number 78)

Options

A. `[Xe]4f^(14) 5d^(9) 6s^(1)`
B. `[Xe]4f^(13) 5d^(9) 6s^(1)`
C. `[Xe]4f^(14) 5d^(10) 6s^(0)`
D. `[Xe]4f^(14) 5d^(8) 6s^(2)`

Explanation

To determine the correct electronic configuration of Platinum (atomic number 78), we can follow these steps:

### Step 1: Identify the Atomic Number
The atomic number of Platinum (Pt) is 78. This means that a neutral platinum atom has 78 electrons.

### Step 2: Determine the Electron Configuration Order
The order of filling the electron orbitals follows the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level to the highest. The order 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
We will fill the orbitals according to the order mentioned above until we reach 78 electrons:
- 1s² = 2
- 2s² = 2
- 2p⁶ = 6
- 3s² = 2
- 3p⁶ = 6
- 4s² = 2
- 3d¹⁰ = 10
- 4p⁶ = 6
- 5s² = 2
- 4d¹⁰ = 10
- 5p⁶ = 6
- 6s² = 2
- 4f¹⁴ = 14
- 5d⁹ = 9
- 6s¹ = 1

Adding these gives us:
2 + 2 + 6 + 2 + 6 + 2 + 10 + 6 + 2 + 10 + 6 + 2 + 14 + 9 + 1 = 78

### Step 4: Write the Electronic Configuration
The electronic configuration for Platinum can be written as:
\[ \text{[Xe]} \, 4f^{14} \, 5d^9 \, 6s^1 \]

### Step 5: Verify Against Given Options
Now, we check the provided options for the electronic configuration of Platinum:
1. [Xe] 4f¹⁴ 5d⁹ 6s¹
2. (other options not provided)

The first option matches our derived electronic configuration.

### Conclusion
The correct electronic configuration of Platinum (Pt) is:
\[ \text{[Xe]} \, 4f^{14} \, 5d^9 \, 6s^1 \]