| what is a conductor | a material that allows the flow of electricity through it |
| what is an insulator | a material that does now allow electrons to easily move through it |
| what is a semi conductor | materials that can act as conductors or insulators under certain conditions |
| how do individual atoms conduct | in conductors the outer energy level is not full
this allows a degree of movement for the electrons |
| why don't individual atoms of an insulator conduct | in an insulator the outer energy level is full and the electrons are not free to move |
| what happens to the energy levels of atoms when they are brought together | the outer energy levels interact with each other to form an energy band |
| what is the conduction band | the highest energy band |
| what is the valence band | the band below the conduction band |
| what is a band gap | space between energy bands |
| describe the energy bands in conductors | valence and conduction band overlap and are both partially filled
valence electrons can move freely through the material |
| in insulators how full is the valence band | completely full of electrons |
| what is the size of the band gap in insulators | very large |
| why don't insulators conduct electricity | at room temperature there is not enough energy to move electrons from the valence band to the conduction band |
| how full is the valence band in semi conductors | completely full |
| what is the size of the band gap in semi conductors | relatively small |
| what happens when you increase the temperature of a semi conductor | electrons are given enough energy to jump the band gap to from the valence band to the conduction band, and so the material conducts |
| explain using band theory why a semiconductor can conduct at room temperature | the band gap in semi conductors is small
some electrons have enough energy to move from the valence band to the conduction band |
