Pick the incorrect statement about the factors affecting ionization energy

Options

A. Half filled or full filled atomic orbitals have high ionization energy
B. More is the shielding of valence electrons more is the ionization energy
C. Larger is the atomic radii lower is ionization energy
D. lonization enthalpy `prop` effective nuclear charge

Answer

To solve the question about the incorrect statement regarding the factors affecting ionization energy, let's analyze each option step by step.

### Step 1: Understand Ionization Energy
Ionization energy is defined as the amount of energy required to remove an electron from the outermost shell of an isolated gaseous atom.

### Step 2: Analyze Each Option
1. **Option A**: "Half filled or fully filled atomic orbitals have high ionization energy."
- **Analysis**: Half-filled (like p³) and fully filled (like p⁶) orbitals are more stable due to symmetry and electron pairing. Therefore, they require more energy to remove an electron. This statement is **correct**.

2. **Option B**: "More is the shielding of valence electrons, more is the ionization energy."
- **Analysis**: Shielding refers to the effect of inner electrons that reduce the effective nuclear charge felt by outer electrons. More shielding means outer electrons feel less attraction from the nucleus, making it easier to remove them, thus lowering ionization energy. This statement is **incorrect**.

3. **Option C**: "Larger is the atomic radii, lower is the ionization energy."
- **Analysis**: As atomic radii increase (moving down a group), the outermost electrons are farther from the nucleus and experience less attraction, making them easier to remove. Therefore, this statement is **correct**.

4. **Option D**: "Ionization energy is directly proportional to effective nuclear charge."
- **Analysis**: Effective nuclear charge (Z_eff) is the net positive charge experienced by valence electrons. A higher Z_eff means a stronger attraction between the nucleus and the electrons, leading to higher ionization energy. This statement is **correct**.

### Conclusion
The incorrect statement among the options is **Option B**: "More is the shielding of valence electrons, more is the ionization energy."