Period 6 element period 6 other metals are incredibly toxic, such as thallium. Period 6 contains the last stable element, lead. All subsequent elements in the periodic table are radioactive. After bismuth, which has a half-life or more than 10 years, polonium, astatine, and radon are some of the shortest-lived and rarest elements known; less than a gram of astatine is estimated to exist on earth at any given time. Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes
British Non-Ferrous Metals Research Association British Non-Ferrous Metals Research Association The British Non-Ferrous Metals Research Association was a research group in the United Kingdom during the 20th century, bringing together public and privately funded research into metallurgy. The name was abbreviated officially to B.N.F.M.R.A. (the organisation was normally known as ‘The BNF’ during its life). It was formed in 1920 by members of the British Non-Ferrous Metals Federation which represented the commercial interests of British manufacturers of coppers and copper alloys, lead, zinc and other non-ferrous metals and their alloys, latterly including titanium. Robert Hutton was appointed director in 1921. The 600 or so subscribing