Metals conduct electricity, and electricity is composed of large numbers of randomly colliding and approximately free electrons. The allowed energy states of an electron are quantized. This quantizati...Metals conduct electricity, and electricity is composed of large numbers of randomly colliding and approximately free electrons. The allowed energy states of an electron are quantized. This quantization appears in the form of very large electron energies, even at T=0K. The allowed energies of free electrons in a metal depend on electron mass and on the electron number density of the metal.