Group 11 element Parkes process. These metals, especially silver, have unusual properties that make them essential for industrial applications outside of their monetary or decorative value. They are all excellent conductors of electricity. The most conductive of all metals are silver, copper and gold in that order. Silver is also the most thermally conductive element, and the most light reflecting element. Silver also has the unusual property that the tarnish that forms on silver is still highly electrically conductive. Copper is used extensively in electrical wiring and circuitry. Gold contacts are sometimes found in precision equipment for their ability to remain corrosion-free. Silver
Period 5 element number increases in the alkali metals, for it is more reactive than potassium, but less so than caesium. In addition, both potassium and rubidium yield almost the same hue when ignited, so researchers must use different methods to differentiate between these two 1st group elements. Rubidium is very susceptible to oxidation in air, similar to most of the other alkali metals, so it readily transforms into rubidium oxide, a yellow solid with the chemical formula RbO. Strontium is the second element placed in the 5th period. It is an alkaline earth metal, a relatively reactive group, although not nearly as