Electron Affinity Calculator
Look up electron affinity values and understand energy changes when atoms gain electrons.
Cl
Chlorine
Atomic Number: 17
Cl(g) + e⁻ → Cl⁻(g)
Electron Affinity:
+349.0 kJ/mol
Energy released (exothermic)
kJ/mol
349.00
eV
3.617
kcal/mol
83.41
Hartree
0.1329
About Electron Affinity
Electron affinity is the energy change when a neutral atom gains an electron to form an anion. Positive values indicate energy is released (exothermic, favorable). Noble gases and elements with stable configurations (like N and Be) have zero or negative electron affinities. Halogens have the highest electron affinities due to their near-complete valence shells.
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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.