The total number of electrons in all bonding molecular orbitals of `O _(2) ^(2-) ` is ...........
(Round off to the nearest integer)

Answer

To find the total number of electrons in all bonding molecular orbitals of the \( O_2^{2-} \) ion, we can follow these steps:

### Step 1: Determine the total number of electrons in \( O_2^{2-} \)

Each oxygen atom has an atomic number of 8, which means it has 8 electrons. Since there are two oxygen atoms in \( O_2^{2-} \):

\[ \text{Total electrons from oxygen} = 2 \times 8 = 16 \]

Additionally, the \( 2- \) charge indicates that there are 2 extra electrons:

\[ \text{Total electrons} = 16 + 2 = 18 \]

### Step 2: Write the molecular electronic configuration

We will fill the molecular orbitals according to the Aufbau principle, starting from the lowest energy level:

1. **\( \sigma 1s \)**: 2 electrons
2. **\( \sigma^* 1s \)**: 2 electrons
3. **\( \sigma 2s \)**: 2 electrons
4. **\( \sigma^* 2s \)**: 2 electrons
5. **\( \sigma 2p_z \)**: 2 electrons
6. **\( \pi 2p_y \)**: 2 electrons
7. **\( \pi 2p_x \)**: 2 electrons
8. **\( \pi^* 2p_y \)**: 1 electron
9. **\( \pi^* 2p_x \)**: 1 electron

### Step 3: Count the electrons in bonding molecular orbitals

The bonding molecular orbitals are:

- \( \sigma 1s \): 2 electrons
- \( \sigma 2s \): 2 electrons
- \( \sigma 2p_z \): 2 electrons
- \( \pi 2p_y \): 2 electrons
- \( \pi 2p_x \): 2 electrons

Now, we sum the electrons in these bonding orbitals:

\[ \text{Total electrons in bonding orbitals} = 2 + 2 + 2 + 2 + 2 = 10 \]

### Final Answer

The total number of electrons in all bonding molecular orbitals of \( O_2^{2-} \) is **10**.

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