First I.P. of Mg is ............. than that of Al

Options

A. Less
B. More
C. Equal
D. None of these

Answer

To determine the first ionization potential (I.P.) of magnesium (Mg) compared to aluminum (Al), we need to analyze their electronic configurations and the factors affecting ionization energy.

### Step-by-Step Solution:

1. **Identify the Atomic Numbers and Electronic Configurations**:
- Magnesium (Mg) has an atomic number of 12. Its electronic configuration is:
\[ \text{Mg: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \]
- Aluminum (Al) has an atomic number of 13. Its electronic configuration is:
\[ \text{Al: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^1 \]

2. **Understand the Concept of Ionization Potential**:
- Ionization potential (I.P.) is the energy required to remove the outermost electron from an atom in its gaseous state.

3. **Analyze the Electron Configuration**:
- In magnesium, the outermost electrons are in the 3s orbital (3s²). In aluminum, the outermost electrons are in the 3s² and 3p¹ orbitals.
- The 3s orbital is filled in magnesium, while aluminum has an additional electron in the 3p orbital.

4. **Consider the Effective Nuclear Charge**:
- The effective nuclear charge experienced by the outermost electrons in magnesium is higher than that in aluminum. This is because the 3p electron in aluminum experiences more shielding from the inner electrons compared to the 3s electrons in magnesium.

5. **Evaluate the Distance from the Nucleus**:
- The 3p electron in aluminum is farther from the nucleus than the 3s electrons in magnesium, leading to a weaker attraction between the nucleus and the outermost electrons in aluminum.

6. **Conclusion**:
- Due to the higher effective nuclear charge and the closer proximity of the outermost electrons to the nucleus in magnesium, it is more difficult to remove an electron from magnesium than from aluminum. Therefore, magnesium has a higher first ionization potential than aluminum.

### Final Answer:
The first ionization potential of magnesium (Mg) is **greater** than that of aluminum (Al).