Question

why electrons doesnt leave the surface of conductors

Answer 1

this is because that the conductors are flow of current  and in the current the electrons are live in discipline when the current is  not flow the electrons are move randomly but not leave their place.

Answer 2

Answer:

There are usually no adjacent grains outside of the conductor, so electrons do not leap out of it unless, for example, another conductor is placed in close contact with it, or the electric field at the surface of the conductor is strong enough to overcome the force keeping electrons inside the grains, or a collision ...