DrDu suggested I posted this here. Wiki says that "The electrons of a single, isolated atom occupy atomic orbitals. Each orbital forms at a discrete energy level. When multiple atoms join together to form into a molecule, their atomic orbitals combine to form molecular orbitals, each of which forms at a discrete energy level. As more atoms are brought together, the molecular orbitals extend larger and larger, and the energy levels of the molecule will become increasingly dense. Eventually, the collection of atoms form a giant molecule, or in other words, a solid. For this giant molecule, the energy levels are so close that they can be considered to form a continuum." I'd like to understand the electronic band of liquid such as h20. What is the ranges of energy than an electron within the h20 molecule may have? Does it form any small bands or just discrete like separate atoms? I know thermal vibrations can break and reform hydrogen bonds very quickly. But they are uniform. Would the electrons wavefunction still somehow form energy bands? to what degree?