The outer electronic configuration of Pd is:

Question

Accepted Answer

The outer electronic configuration of palladium (Pd) is given as Option 4: $4d^{10}5s^{0}$. Let's explore why this is the correct configuration and why the other options are incorrect.

### Explanation for Option 4: $4d^{10}5s^{0}$

Palladium (Pd) has an atomic number of 46. In general, the electron configuration of elements is determined by the Aufbau principle, Hund's rule, and the Pauli exclusion principle. According to these principles, electrons fill orbitals starting from the lowest energy level to the highest.

For palladium, the expected electron configuration would be $ [Kr] 4d^{8}5s^{2} $. However, palladium is an exception to the typical filling order due to the stability associated with a completely filled d-subshell. The $4d$ subshell can hold a maximum of 10 electrons. In the case of palladium, the electrons rearrange to completely fill the $4d$ subshell, resulting in the configuration $4d^{10}5s^{0}$. This configuration is more stable due to the full $4d$ subshell, which provides additional stability to the atom.

### Why Other Options are Incorrect:

1. **Option 1: $4d^{8}5s^{2}$**
   - This configuration follows the expected filling order without considering the stability provided by a full $4d$ subshell. However, palladium is an exception where the $4d$ subshell is completely filled, making this option incorrect.

2. **Option 2: $4d^{9}5s^{1}$**
   - This configuration suggests that the $4d$ subshell is not fully filled, which does not provide the same level of stability as a completely filled $4d$ subshell. Palladium achieves greater stability with a full $4d$ subshell, making this option incorrect.

3. **Option 3: $4d^{10}5s^{2}$**
   - This configuration implies that both the $4d$ and $5s$ subshells are fully occupied. However, palladium achieves its stable state by having a full $4d$ subshell and an empty $5s$ subshell. Therefore, this option is incorrect.

In conclusion, Option 4: $4d^{10}5s^{0}$ is the correct electronic configuration for palladium, as it reflects the stability achieved by a completely filled $4d$ subshell, which is a known exception to the typical electron filling order.