SSC MTS EXAM

Detailed explanation-1: -The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.

Detailed explanation-2: -Elements with the same number of valence electrons in their outermost orbit are placed in the same group of the periodic table. These elements are referred to as families because both the physical and chemical properties of elements lying the same group are similar. For example all group.