1234. I am doing a science fair project on conductors and insulators. What are some of the best and worst conductors of electricity? — LM
The best conventional conductors are silver, copper, gold, and aluminum. What makes them good conductors is that electrons move through them for relatively long distances without colliding with anything that wastes their energy. These materials become better conductors as their purities increase and as their temperatures decrease. A cold, near-perfect crystal is ideal, because all of the atoms are then neatly arranged and nearly motionless, and the electrons can move through them with minimal disruption. However, there is a class of even better conductors: the so-called "superconductors." These materials allow electric current to travel through them will absolutely no loss of energy. The carriers of electric current are no longer simply independent electrons; they are typically pairs of electrons. Still, superconductivity appears because the moving charged particles can no longer suffer collisions that waste their energy-they move with perfect ease. We would be using superconductors everywhere in place of copper or aluminum wires if it weren't for the fact that superconductors only behave that way at low temperatures.
As for the best insulators, I'd vote for good crystals of salts like lithium fluoride and sodium chloride (table salt), and covalently-bound substances like aluminum oxide (sapphire) or diamond. All of these materials are pretty nearly perfect insulators.