Question

Periodic change in electronic configuration is responsible for the physical and chemical properties of element. Justify this statement.

Answer 1

• The electronic configuration of the elements changes periodically in a period and group as well.
• We could find a pattern in the physical and chemical properties as we go down in a group or move across a period. 
• For example : The chemical reactivity is high at the beginning, lower at the middle and increases to a maximum at group 17 in a period. 
• The reactivity increases on moving down the group of alkali metals. But the reactivity decreases on moving down the group of halogens. 
• Atomic radii increases down the group and decreases across the period.