" 1.Why do elements of the same group have similar physical and chemical properties "

Why do elements in the same period have different physical and chemical properties? What about elements in the same group?

Physical and Chemical Properties of Group 16

Identify the elements which have similar physical and chemical properties as the element Y.

Assertion: Elements belonging to the same group show similarity in chemical properties. Reason: Elements of the same group have same number of valence electrons.

The element with atomic number 19 is similar in physical and chemical properties to the element with atomic number