Question

The electron affinity for bromine is negative. Why

Answer 1

The energy released when an electron is added to the outermost shell of 1 mole of atoms in gaseous state generates 1 mole of 1- ions in gaseous state, is called the electron affinity.

The electron affinity is a measure of the attraction between the electron added to the outer shell and the core of the atom. The energy released is more when the attraction is stronger.

Br + e à Br^- E= - 324 kJ/mol

It is the energy released per mole of Br, when this anion formation takes place.

First electron affinities have negative values for the group 6 and 7 elements. The negative sign indicates that the energy is released when an electron is added to Br atom to make a Br^- anion(Octet filled) in gaseous state.