How does it very in a group and in a period ?

Define electron gain enthalpy. How it varies in a group and in a period ? Why is the electron gain enthalpy of O or F is less negative than that of succeeding element in the group ?

What is periodic property? How the following properties vary in a group and in a period? Explain. Metallic character.

What is a periodic property? How the following properties vary in a group and in a period? Expain (a) Atomic radius.

What is a periodic property? How the following properties vary in a group and in a period? Explain (b) EN.

What is a periodic property? How the following properties vary in a group and in a period? Explain (a) IP.