What units is electron affinity measured in?
Scientists measure electron affinity in joules.
Electron affinity, EA measures the energy released when an electron adds to a gaseous atom.
It is usually reported as the energy per mole of atoms (in units of kilojoules per mole). For example,
Cl(g) + e⁻ → Cl⁻(g); EA = -349 kJ/mol
The negative sign shows that energy is released when a Cl atom gains an electron.