Following the Mulliken scale, what parameters are required to evaluate electronegativity ?

Options

A. Only electronegativity
B. Only electron affinity
C. Electron affinity and ionization energy
D. Ionic potential and electronegativity

Explanation

To evaluate electronegativity following the Mulliken scale, we need to consider the following parameters:

### Step-by-Step Solution:

1. **Understanding Electronegativity**:
- Electronegativity is defined as the ability of an atom to attract shared electrons in a chemical bond. It indicates how strongly an atom can pull electrons towards itself.

2. **Mulliken Scale Definition**:
- The Mulliken scale provides a way to quantify electronegativity based on two key concepts: electron affinity and ionization energy.

3. **Key Parameters**:
- **Electron Affinity (EA)**: This is the energy change that occurs when an electron is added to a neutral atom in the gas phase. It reflects how much an atom wants to gain an electron.
- **Ionization Energy (IE)**: This is the energy required to remove an electron from a neutral atom in the gas phase. It indicates how strongly an atom holds onto its electrons.

4. **Mulliken Electronegativity Formula**:
- According to the Mulliken scale, the electronegativity (Xm) can be calculated using the formula:
\[ Xm = \frac{IE + EA}{2} \]
- This formula shows that the electronegativity is the average of the ionization energy and electron affinity.

5. **Conclusion**:
- Therefore, the parameters required to evaluate electronegativity according to the Mulliken scale are **electron affinity** and **ionization energy**.

### Final Answer:
The parameters required to evaluate electronegativity following the Mulliken scale are **electron affinity and ionization energy**.

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