Why does every chemical reaction require a certain amount of activation energy

Every chemical reaction requires a minimum amount of energy to undergo reaction.

The total energy required is Threshold energy. The chemicals have some internal energy and they require some extra energy which is known as activation energy.

The reaction occurs when two molecules or atoms come closer to each other and for this they need kinetic energy.

Now for an effective collision the two molecules or atoms should collide with a minimum amount of energy so that they may undergo reaction so again they need some energy

These kinetic energy and energy for effective collision is actually called as activation energy.