text: Under the free electron model, the electrons in a metal can be considered to form a uniform Fermi gas. The number density  of conduction electrons in metals ranges between approximately 10 and 10 electrons per m, which is also the typical density of atoms in ordinary solid matter. This number density produces a Fermi energy of the order:
  where m is the electron rest mass. This Fermi energy corresponds to a Fermi temperature of the order of 10 kelvins, much higher than the temperature of the Suns surface. Any metal will boil before reaching this temperature under atmospheric pressure. Thus for any practical purpose, a metal can be considered as a Fermi gas at zero temperature as a first approximation (normal temperatures are small compared to T').