Calculate the ionization energy in eV/atom) of fluorine if its electronegativity on Pauling's scale is 4 and its electron gain enthalpy is -3.4 eV/atom.
(Add the digits till you get single digit answer.) 

Answer

To calculate the ionization energy of fluorine based on its electronegativity and electron gain enthalpy, we can use the following relationship:

1. **Understanding the relationship**: The ionization energy (IE) can be estimated using the formula:
\[ \text{IE} = \text{Electronegativity} + \left(-\frac{\text{Electron Gain Enthalpy}}{2}\right) \]

2. **Substituting the values**: We know from the question:
- Electronegativity (χ) of fluorine = 4
- Electron gain enthalpy (EGE) = -3.4 eV/atom

Now, substituting the values into the formula:
\[ \text{IE} = 4 + \left(-\frac{-3.4}{2}\right) \]

3. **Calculating the electron gain enthalpy term**:
\[ -\frac{-3.4}{2} = \frac{3.4}{2} = 1.7 \]

4. **Adding the values**:
\[ \text{IE} = 4 + 1.7 = 5.7 \text{ eV/atom} \]

5. **Adding the digits to get a single digit**:
- The digits of 5.7 are 5 and 7. Adding them gives:
\[ 5 + 7 = 12 \]
- Now, adding the digits of 12 gives:
\[ 1 + 2 = 3 \]

Thus, the final answer for the ionization energy of fluorine, reduced to a single digit, is **3**.