Those substances which have the ability to carry charge from one place to another are called conductors. Silver is one of the best conductors. There are lots of examples of conductors like aluminum, coal, iron, copper, etc. Some conductors are solid and some are liquids. Examples of liquid conductors are acid alkalis, salt solution etc. Our body is also a good conductor of electricity. That’s why sometimes we get shocked by some of the electric appliances. Conductivity of a body depends upon the no of free electrons present inside it. More the number of electrons more is the conductivity.
So, in metallic conductors there are large number of free electrons. In an atom one or more electrons can be movable but they did not leave the atom shells at any cost. So, under the normal conditions they do not become absent from the metal.
But in the liquid conductors the charge carriers are the moving ions.