Mulliken Electronegativity Scale (Mulliken EN ~ average of ionization energy and electron affinity (consistent sign)
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Mulliken EN ~ average of ionization energy and electron affinity (consistent sign convention required)
What each symbol means
| Symbol | What it stands for |
|---|---|
| I_1 | First ionization energy (positive magnitude in eV when using positive IP convention) |
| E_ea | Electron affinity — use the convention given (often positive magnitude for energy released on adding e⁻) |
| \chi_M | Mulliken electronegativity in eV scale |
When to use this
JEE problems usually specify values so signs are unambiguous. If EA is given as ‘energy released’ as a positive number, Mulliken uses χ_M = (IP + EA)/2 in eV. If Δ_egH sign convention appears, convert carefully.