10⁻⁸10⁻⁴10⁰10⁴10⁸10¹²10¹⁶10²⁰10²⁴resistivity, ohm-metres (log scale)silver, copperaluminiumironnichromegraphiteseawaterpure siliconpure waterglassrubberquartzPTFEsemiconductorsinsulatorsconductors
Resistivity is how strongly a material resists current, independent of its shape. It spans a wider range than almost any other property: PTFE, the plastic in non-stick pans, resists current about 10³¹ times more strongly than silver. Metals sit at the far left because each atom contributes a free electron. Insulators sit at the far right because none of their electrons are free. Semiconductors like silicon sit in between, and a trace of impurity can move them a long way along the scale.