Silver has a brilliant

Silver has a brilliant white metallic luster that can take a high polish,[11] and which is so characteristic that the name of the metal itself has become a colour name.[8] Unlike copper and gold, the energy required to excite an electron from the filled d band to the

s-p conduction band in silver is large enough (around 385 kJ/mol) that it no longer corresponds to absorption in the visible region of the spectrum, but rather in the ultraviolet; hence silver is not a coloured metal.[8] Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm.[12] At wavelengths shorter than 450 nm, silver’s reflectivity is inferior to that of aluminium and drops to zero near 310 nm.[13]

Very high electrical and thermal conductivity are 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.[14] The thermal conductivity of silver is among the highest of all materials, although the thermal conductivity of c

arbon (in the diamond allotrope) and superfluid helium-4 are even higher.[7] The electrical conductivity of silver is the highest of all metals, greater even than copper. Silver also has the lowest contact resistance of any metal.[7] Silver is rarely used for its electrical conductivity due to its high cost, although an exception is in radio-frequency engineering, particularly at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior. During World War II in the US, 13540 tons of silver were used for the electromagnets in calutrons for enriching uranium, mainly because of the wartime shortage of copper.[15][16][17]