Why does magnesium form `Mg^(2+)` and not `Mg^(+)`?

Options

A. Magnesium (II) is insoluble in water
B. Commonly higher oxidation states are preferred by metals
C. lonic radius of Mg(II) is samller than that of Mg(I)
D. High hydration energy as well as high latice

Answer

To understand why magnesium forms \( \text{Mg}^{2+} \) instead of \( \text{Mg}^{+} \), let's analyze the electronic configuration and the principles governing ion formation.

### Step-by-Step Solution:

1. **Identify the Atomic Number and Electronic Configuration of Magnesium**:
- Magnesium (Mg) has an atomic number of 12.
- Its electronic configuration is \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \).

**Hint**: Recall that the atomic number indicates the number of protons and electrons in a neutral atom.

2. **Determine the Valence Electrons**:
- The outermost shell (n=3) of magnesium contains 2 electrons in the \( 3s \) subshell.

**Hint**: The number of valence electrons can be found by looking at the highest energy level in the electronic configuration.

3. **Understanding the Octet Rule**:
- The octet rule states that atoms tend to gain, lose, or share electrons to achieve a full outer shell, typically consisting of 8 electrons.

**Hint**: Consider how atoms achieve stability through electron transfer.

4. **Electron Loss and Ion Formation**:
- Magnesium can lose its 2 valence electrons to achieve a stable electronic configuration similar to neon (the nearest noble gas), which has a full outer shell of 8 electrons.

**Hint**: Think about the stability of noble gases and how losing electrons can help achieve that stability.

5. **Formation of \( \text{Mg}^{2+} \)**:
- By losing 2 electrons, magnesium forms the ion \( \text{Mg}^{2+} \).
- The formation of \( \text{Mg}^{+} \) would leave it with only 11 electrons, resulting in an unstable configuration.

**Hint**: Consider the energy required to remove electrons and how it relates to stability.

6. **Lattice Energy and Hydration Energy**:
- The formation of \( \text{Mg}^{2+} \) is favored due to high lattice energy and hydration energy associated with the \( \text{Mg}^{2+} \) ion compared to \( \text{Mg}^{+} \).

**Hint**: Lattice energy is the energy released when ions form a solid lattice, while hydration energy is the energy released when ions are solvated by water.

### Conclusion:
Magnesium forms \( \text{Mg}^{2+} \) instead of \( \text{Mg}^{+} \) because it loses 2 electrons to achieve a stable octet configuration, which is energetically favorable due to high lattice and hydration energies.