Band Gaps in Conductors and Insulators

Band gaps in solids help explain why some materials conduct electricity and others do not. When many atoms come together, their atomic orbitals combine into molecular orbitals with distinct energies. In a solid, so many orbitals are involved that these energies merge into continuous regions called bands.

Band theory is similar to molecular orbital theory and provides a model for electronic behavior in solids.

Recall that when two or more atoms come together to become a molecule, their atomic orbitals overlap to form molecular orbitals of discrete energy levels. As the number of atoms in the molecule increases, so does the number of molecu...