Metals are good conductors of electricity and heat because they have an abundance of electrons. These electrons are free, and can move freely throughout the metal. The highest number of free electrons is in pure silver, which is extremely expensive. Copper is next in line, but both of these metals have high levels of free electrons. Copper is also an excellent conductor of heat. Copper also has the highest density of free electrons per atom.
Alloys, on the other hand, are poor conductors of heat and electricity. Alloys are made by adding foreign atoms to the metal, which increase the irregularities and block the free motion of electrons. The result is that alloys are poor conductors of electricity. Metals that can conduct heat and electricity well are copper, silver, and zinc. By contrast, glass and aluminum conduct electricity and heat but not electricity.
What makes metals good conductors? It is due to their free electrons. When heated, their molecules and particles pick up energy and pass it on to nearby particles. This process continues from the hot to the cold end of a metal. The energy transfer is due to the fact that electrons in metals are free-moving, delocalized particles, and move more freely when they gain energy. These free electrons pass the energy to nearby particles more quickly.
In addition to their high conductivity, metals are also good conductors of heat. Heat is a form of kinetic energy, and the atoms in metals possess a large number of electrons. When heated, these electrons begin to vibrate more vigorously, causing the material to pass heat more efficiently. This causes heat and electricity to propagate through the metal. It is not only heat that is transferred via metals, but the energy that is stored in these materials.