Silver metal. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm. Very high electrical and thermal conductivity is common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions (which occur in the preceding transition metals) lower electron mobility. The electrical conductivity of silver is the greatest of all metals, greater even than copper, but it is not widely
Thermal conductivity the molar volume. More rigorously, the mean free path of a molecule in a gas is given by formula_77 where "σ" is the collision cross section. So The heat capacity per particle "c" and the cross section "σ" both are temperature independent so the temperature dependence of "k" is determined by the "T" dependence of "v". For a monatomic gas, with atomic mass "M", "v" is given by formula_79 So This expression also shows why gases with a low mass (hydrogen, helium) have a high thermal conductivity. For metals at low temperatures the heat is carried mainly by the free