WHICH ARE THE ELEMENT OF LOWEST AND HIGHEST ELECTRON AFFINITY?

The electron affinity is a measure of the energy change when an electron is added to a neutral atom to form a negative ion. For example, when a neutral chlorine atom in the gaseous form picks up an electron to form a Cl- ion, it releases an energy of 349 kJ/mol or 3.6 eV/atom. It is said to have an electron affinity of -349 kJ/mol and this large number indicates that it forms a stable negative ion. Small numbers indicate that a less stable negative ion is formed. Groups VIA and VIIA in the periodic table have the largest electron affinities.

* Alkali earth elements (Group IIA) and noble gases (Group VIIIA) do not form stable negative ions.

Period 2	Li		B		C		N		O		F
	-0.62		-0.28		-1.27		0		-1.43		-3.41

Period 3	Na		Al		Si		P		S		Cl
	-0.55		-0.46		-1.39		-0.75		-2.08		-3.62