Periodic Table and Elements

The element with the highest electron affinity is

When an atom gains electron, energy is given off and this energy is known as electron affinity for that particular atom or molecule. Electron affinity is defined as the energy released when an electron is added to a gaseous atom or ion. 

T + e- =  T-

Cl + e^--= Cl^1- 

(Ne)3s²3p⁵------>(Ne)3s²3p⁶

Which of the following factors does not effect the metallic character of an element?

When an element shows properties like loosing electrons easily, getting reduced easily, formation of ionic halides and basic oxides and has the ability to displace hydrogen from dilute acids, it is considered to be a metal. Metallic character decreases across a period. This occurs because atoms accept electrons more readily to fill the valence shell than loosing one. Metallic character increases while moving down a group because atoms lose electrons more easily because of the increase in the atomic radii, resulting in decrease in the attraction between nucleus and valence electrons.

An atom of which of the following elements has the greatest ability to attract electrons?

The ability of attracting electrons of any element is called electronegativity of that element. Electronegativity is affected by both its atomic number as well as the distance between its nucleus and the valence shell electrons. The higher the value of electronegativity, more electrons get attracted. It is a dimensionless quantity, commonly referred to as the Pauling scale on a relative scale starting from 0.7 to 3.98.