Electron Affinity Calculator

Compare electron affinities of elements in kJ/mol and eV. Predict anion formation tendency.

Compare Elements

Halogens (Highest EA):

Higher Electron Affinity

Cl

Difference: 21.0 kJ/mol

1Cl EA
349 kJ/mol
2F EA
328 kJ/mol
eVCl in eV
3.617 eV
eVF in eV
3.399 eV

Cl

Exothermic

Anion: Favorable

F

Exothermic

Anion: Favorable

Understanding Electron Affinity

Electron affinity (EA) is the energy change when an electron is added to a neutral atom in the gas phase. A positive EA means energy is released (exothermic) when an electron is gained. Halogens have the highest electron affinities because gaining one electron completes their octet.

Noble Gases

EA = 0 (full valence shell)

Nitrogen Anomaly

Negative EA due to half-filled p orbitals

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Editorial Note

MyCalcBuddy Editorial Team

This page is maintained as an educational calculator reference.

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Formula Source: Chemistry: The Central Science

by Brown, LeMay, Bursten

🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.