Choose the correct order of the property given below:

Options

A. `N^(3-) lt O^(2-)` : Ionic radius
B. `N gt O`: First ionization energy
C. `N gt O`: Second ionization energy
D. `N gt O`: Electron affinity order

Answer

To solve the question regarding the correct order of the properties of N3- and O2- ions, we will analyze the ionic radius, ionization energy, and electron affinity step by step.

### Step 1: Compare Ionic Radius of N3- and O2-
1. **Understanding Ionic Radius**: The ionic radius of an anion increases with the increase in negative charge. This is because additional electrons repel each other, causing the electron cloud to expand.
2. **Comparison**:
- N3- has three extra electrons compared to its neutral nitrogen atom, while O2- has two extra electrons compared to its neutral oxygen atom.
- Therefore, N3- will have a larger ionic radius than O2-.

**Conclusion**: The order of ionic radius is N3- > O2-.

### Step 2: Compare Ionization Energy of Nitrogen and Oxygen
1. **Understanding Ionization Energy**: Ionization energy is the energy required to remove an electron from an atom. It is influenced by the effective nuclear charge (Z-effective) and the size of the atom.
2. **Comparison**:
- Nitrogen (N) has the electronic configuration of 1s² 2s² 2p³, while oxygen (O) has 1s² 2s² 2p⁴.
- Although oxygen is smaller in size and has more nuclear charge, nitrogen has a half-filled p subshell (2p³), which is more stable and thus requires more energy to remove an electron compared to oxygen.

**Conclusion**: The order of ionization energy is N > O.

### Step 3: Compare Electron Affinity of Nitrogen and Oxygen
1. **Understanding Electron Affinity**: Electron affinity is the energy change when an electron is added to a neutral atom. It is influenced by the effective nuclear charge and the size of the atom.
2. **Comparison**:
- Oxygen has a higher electron affinity than nitrogen because it is closer to achieving a stable octet configuration (2p⁶) after gaining one electron.
- Nitrogen, being less electronegative and having a half-filled p subshell, does not release as much energy when gaining an electron compared to oxygen.

**Conclusion**: The order of electron affinity is O > N.

### Final Summary
- Ionic Radius: N3- > O2-
- Ionization Energy: N > O
- Electron Affinity: O > N