Why are metals generally good conductors of electricity?

Metals are excellent conductors of electricity because their atomic structure allows outer electrons to be very loosely bound to the nucleus. These loosely bound electrons are known as "free electrons" because they can easily break away and move from one atom to another. When a voltage is applied across a metal wire, these free electrons drift through the material, creating an electric current. This abundance of mobile charge carriers is what makes metals like copper, silver, and aluminum so effective at conducting electricity. Common distractors try to trick you with other physical properties. Protons are tightly locked in the atomic nucleus and do not move to create current. Density and Young’s modulus are mechanical properties related to a material's mass and stiffness, respectively, and have nothing to do with electrical conductivity.