Seniors - Check out Band Theory

As we get into electricity, materials become important, with the big 3 being insulators/nonconductors; conductors (usually metals); and semiconductors. To begin understanding why there are different electrical properties, we have something called Band Theory, coming from quantum mechanics and the notion of energy levels for atoms. Check out this video to get a hopefully clear conceptual understanding of what these 'bands' are that we'll refer to.