Element 82 in our International Year of the Periodic Table series is lead. Lead and its compounds have previously been used in petrol, water pipes and paints, though its toxicity has led many of its uses being discontinued. It’s still used in car batteries and bullets.
Element 81 in our International Year of the Periodic Table series is thallium. Thallium and its compounds are toxic, which limits their uses, though in the past it’s been used as a rat poison and in some types of thermometers.
Element 80 in our International Year of the Periodic Table series is mercury. Mercury is the only metal which is liquid at room temperature and has a reputation for toxicity.
Element 79 in our International Year of the Periodic Table series is gold. Gold compounds have been used to treat arthritis in the past. Gold is also used as a food additive and found in large quantities dissolved in the oceans.
Element 78 in our International Year of the Periodic Table series is platinum. Platinum is found in compounds used as key anti-cancer drugs and it also one of several metals used in catalytic converters.
Element 77 in our International Year of the Periodic Table series is iridium. Iridium is used in pen tips, compasses and spark plugs, and provides a key clue to what wiped out the dinosaurs.