How does the electron gain enthalpy values vary in a group and a period ?

Define electron gain enthalpy. Explain why electron gain enthalpies of some elements are positive. How does electron gain enthalpy vary in a group and in a period ?

How does the ionization energy vary in a group and a period ?

How does the metallic character of the elements vary (i) in a group, (ii) in a period of the modern periodic table ?

How does electronegativity vary in a group and period ?

How does atomic radius vary down a group and along a period?

How does metallic character vary in the group and period?

Electron gain enthalpy is an important periodic property. a) What is meant by electron gain enthalpy? b) What are the factors affecting electron gain enthalpy? c) How electron gain enthalpy varies on moving across a period? Justify.

What do you mean by the term electron gain enthalpy? How does electron gain enthalpy change along a period and in a group?