The space between the outermost filled energy band and the next empty band is called

The space between the outermost filled energy band and the next empty band is called the Band Gap.

Step 1: Understand the structure of an atom. Atoms have a nucleus, which contains protons and neutrons, and they have shells, which contain electrons.

Step 2: Understand energy bands. In a solid, the electrons are not associated with a single atom, but are able to move within the entire solid. The energy levels that these electrons can occupy form bands.

Step 3: Identify the filled and empty energy bands. The outermost filled energy band is called the valence band. This is the highest energy band that is filled with electrons at absolute zero temperature. The next empty band is called the conduction band. This is the lowest energy band that is empty of electrons at absolute zero temperature.

Step 4: Understand the band gap. The band gap is the energy difference between the top of the valence band and the bottom of the conduction band. Electrons must obtain this energy in order to move from the valence band to the conduction band.

So, the space between the outermost filled energy band (valence band) and the next empty band (conduction band) is called the Band Gap.