Electron affinity reflects the ability of an atom to accept an electron. It is the energy change that occurs when an electron is added to a gaseous atom. Atoms with stronger effective nuclear charge have greater electron affinity.
- Group II a elements the alkaline earth have low electron affinity value. These elements are relatively stable because they have filled S subshells.
- Group VII A elements the halogens have high electron affinity because the addition of an electron to an atom results in a completely filled shell.
- Group VIII A elements of noble gases have electron affinities near zero. Because each atom posses a stable octet and will not accept an electron readily. Elements of other groups have low electron affinity.