1. Electronegativity is the property of an atom that attracts the shared pair of an electron to itself.
2. Electronegativity increases and decrease. It increases when to you from to the side or across of a period because the number of charge in the nucleus increases. Electronegativity decreases when you move down in a group because the electrons move farther or become far from the nucleus's pull.
I hope it helps! Have a great day!