Be and Mg have zero value of electron affinity, because

Options

A. Be and Mg have `[He]2s^(2)` and `[Ne]3s^(2)` configuration respectively.
B. 2s and 3s orital are filled to their capacity.
C. Be and Mg are unable to accept electron.
D. All the above are correct.

Explanation

To solve the question of why Beryllium (Be) and Magnesium (Mg) have a zero value of electron affinity, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Electron Affinity**:
- Electron affinity is defined as the amount of energy released when an electron is added to a neutral atom in the gaseous state. A higher electron affinity indicates a greater tendency to accept an electron.

2. **Determine the Electronic Configurations**:
- For Beryllium (Be), with an atomic number of 4:
- The electronic configuration is: 1s² 2s²
- For Magnesium (Mg), with an atomic number of 12:
- The electronic configuration is: 1s² 2s² 2p⁶ 3s²

3. **Identify the Filled Orbitals**:
- In Beryllium, the 2s orbital is completely filled (2 electrons).
- In Magnesium, the 3s orbital is also completely filled (2 electrons).

4. **Reason for Zero Electron Affinity**:
- Atoms with completely filled orbitals are generally stable and do not have a tendency to gain additional electrons.
- Since both Be and Mg have filled s-orbitals, they do not favor the addition of an electron, leading to a zero value of electron affinity.

5. **Conclusion**:
- Therefore, the reason Beryllium and Magnesium have zero electron affinity is due to their completely filled s-orbitals, making them unable to accept an additional electron.