Question

why alkalis are good electrical conductors

Answer 1

These are the good electrical conductors because of the presence of the water in them as they are formed by the reaction with water. They contain OH- ions in them also.

Answer 2

Alkali metals are good conductors of heat. ... ALL metals are good conductors of heat. (see exception below) This is probably because the electrons in the hot environment gain kinetic energy and can easily move from atom to atom - thereby moving the kinetic energy around.