Explanation:
Elements present in vertical columns of a periodic table represent a group or a family.
For example, elements of group 2 are beryllium, magnesium, calcium, strontium, barium, and radium.
Elements of a group have same number of valence electrons due to which they show same chemical properties.
Whereas elements present in a horizontal line depicts period in a periodic table.
For example, lithium, beryllium, boron and carbon they all belong to period 2 of the periodic table.
Hence, we can conclude that a vertical column within the periodic table represents a family or group.
