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 reciprocal of thermal conductivity is called thermal resistivity. The general equation for thermal conductivity is formula_1, where formula_2 is the heat flux, formula_3 is the thermal conductivity and formula_4 is the temperature gradient. In the International System of Units (SI), thermal conductivity is measured in watts per meter-kelvin (W/(m⋅K)). Some papers report in watts per centimeter-kelvin (W/(cm⋅K)). In imperial units, thermal conductivity is measured in BTU/(hr⋅ft⋅°F). The dimension of thermal conductivity is MLTΘ, expressed in terms of the dimensions mass (M), length (L), time (T), and temperature (Θ). Other units which are closely related to the thermal conductivity are in