Question

why atomic hydrogen is more reactive than molecular hydrogen? detailed in simple way

Answer 1

We’ll first off atomic hydrogen is incredibly unstable. Its like a 20 year old virgin who wants to get his/her first; it will do whatever it has to to become stable. Molecular hydrogen as you can imagine fills up the 1S orbital and completed the shell making it very stable and not as likely to hook up with other reactions. When dealing with reactivity four things are key.

StabilityConformation (Geometric Hindrances)Energy of systemReaction rate

I say reaction rate because the energy released when bonds break (after the hump is crosses) can chain further reactions, it something is slow it might not have the same “reactivity)

All of this stems from the Gibbs Free Energy relationship