Question

Why are metals good conductors of electricity?

Answer 1

In metals, electrons are freely held because they form metallic bonds with each other. In a metallic bond, instead of a bond created by sharing electrons  just between two atoms, electrons are shared between many atoms of the element of a metal. This creates a sea of electrons that makes it very easy for energy in the form electricity to move through the metal.

In most elements, atoms hold tightly to their atoms but in most metals, atoms hold their electrons rather loosely. 

Answer 2

Metals are good conductors because the molecules that are inside the metal are tightly packed together. This is why the heat moves through the metal quickly.