Question

why chemical reactivity in period first decreases and then increases.

Answer 1

here is ur answer . thanks for asking

Answer 2

The group 1 electron can easily lose an electron than group 2. Similarly group 2 than group 3. So reactivity decreases first. But from group 5 to 7 have a tendency to gain electrons. Group 7 can easily gain than group 6. Similarly group 6 than 5. So their reactivity increases as group 5 are slow(in gaining electrons) than 6 and 7. So the chemical reactivity first decreases and then increases.