Question

what is electronegativity?how does it compare with electron affinity

Answer 1

Electronegativity is the tendency to gain an electron or to pull a shared electron toward itself. e.g. Cl is an electronegative element. Electronegativity devreases down a group amd increases across a period.
Electron affinity is closely related to Electronegativity. Electron affinity can be called as the 'measure' of Electronegativity, but is not the same as it.
For example Flourine is more electronegative than chlorine , but has less electron affinity than chlorine.
Electron affinity depends upom the number of electrons in the outermost subshell/ shell. It can be defined as the energy gained by a neutral, gaseous isolated atom when it absorbs an electron to become an ion. It is also called as electron gain enthalpy.