The electronic configuration of terbium (IV) (At. No. 65) is

Options

A. `[Xe] 4f^(5) 6s^2`
B. `[Xe]4f^(7) 6s^0`
C. `[Xe] 4f^(8) 6s^0`
D. `[Xe] 4f^(7) 6s^2`

Explanation

To determine the electronic configuration of terbium in its +4 oxidation state (Tb^4+), we can follow these steps:

### Step 1: Determine the Atomic Number and Ground State Configuration
- The atomic number of terbium (Tb) is 65.
- The ground state electronic configuration of terbium can be derived from the order of filling of orbitals according to the Aufbau principle. For atomic number 65, the configuration is:
- [Xe] 4f^9 6s^2
- Here, [Xe] represents the electron configuration of xenon, which accounts for the first 54 electrons.

### Step 2: Identify the Oxidation State
- The question specifies that we need the configuration for Tb^4+. This means we need to remove 4 electrons from the ground state configuration.

### Step 3: Remove Electrons According to Energy Levels
- When removing electrons, we first remove from the outermost shell (the highest energy level). In this case, we remove 2 electrons from the 6s subshell and 2 electrons from the 4f subshell:
- Remove 2 electrons from 6s^2 → 6s^0
- Remove 2 electrons from 4f^9 → 4f^7

### Step 4: Write the Final Electronic Configuration
- After removing the electrons, the electronic configuration for Tb^4+ will be:
- [Xe] 4f^7 6s^0

### Conclusion
- Therefore, the electronic configuration of terbium in the +4 oxidation state (Tb^4+) is:
- **[Xe] 4f^7 6s^0**