Question

State the trend in chemical reactivity :

(i) across the period left to right

Answer 1

• The chemical reactivity of elements mainly depends on the tendency to lose or gain electrons to complete their octet.
• On moving from left to right in a period, the chemical reactivity of elements first decreases then increases.

For example: In third period, from left to right as the tendency to lose electrons decreases, reactivity also decreases. Thus, silicon is the least reactive element in the third period. As we move from phosphorus to chlorine, the tendency to gain electron increases, hence reactivity again increases.