For most substances, the density of the solid form is slightly greater than the density of the liquid form. Water, however, is different. It is slightly less dense in the solid form than it is in the liquid form. Compare water in the solid form with neon, argon, and oxygen, and propose a reason why solid water is less dense than liquid water.

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?