HELP on ELECTRICAL RESISTIVITY of METALS, ∞Ohm-cm (micro Ohm-centimetre) @ NTP
The electrical resistivity is the ability of the material to resist the conduction of electricity. It is the reciprocal of the conductivity. The electrical resistivity of a metal or electrical conductor depends strongly upon the temperature (see temp. coeff. of resistivity), with the resistivity decreasing with decreasing temperature until it reaches a fixed value at cryogenic temperatures. The electrical conductivity depends heavily on the availability of free electrons, for it is the overall movement (drift) of electrons in one particular direction within a metal by the application of an external electric field (or voltage) which constitutes the conduction of an electrical current.
Of the metals, Manganese has the greatest resistivity of 185∞┘-cm, followed closely by Gadolinium and Plutonium at 141, then Mercury at 94. The Lanthanide rare earths have fairly high resistivities of approximately 100. The resistivities of the transition metals are all very low except for Manganese and Mercury, and Zinc and Titanium, with the transition elements of group 11 having the lowest resistivities, the lowest of which being Silver at 1.6, next Copper at 1.7, followed by Gold at 2.4.
The transition metals, with unfilled d-shells, have the highest resistivities because the s-electrons are scattered by collisions with the d-electrons, that cannot occur when the d-shell is filled. Thus the resistivities of nickel, palladium and platinum with un-filled d-shells are five times higher than the corresponding elements copper, silver and gold with filled d-shells immediately adjacent to them in the periodic table.
