Praseodymium
Praseodymium is a soft, silvery, yellowish rare earth metal, atomic number 59. Its name comes from Greek for green twin (prasios didymos) - it produces green compounds. Used in hig…
Elements
Pure substances that cannot be broken down by chemical means
118 chemicals in this category
Promethium
Promethium is a radioactive rare earth metal, atomic number 61. The only lanthanide with no stable isotopes. Produced in nuclear reactors. Named after the Greek Titan Prometheus. P…
Protactinium
Protactinium is a rare, highly toxic and radioactive actinide metal. Its name means 'parent of actinium' as it decays into actinium. It is one of the rarest and most expensive natu…
Radium
Radium is a radioactive alkaline earth metal discovered by Marie and Pierre Curie in 1898. It was historically used in luminous paints and medical treatments but was phased out onc…
Radon
Radon is a colourless, odourless, radioactive noble gas, atomic number 86. The heaviest noble gas. Produced by radioactive decay of radium. Second leading cause of lung cancer (aft…
Rhenium
Rhenium is a dense, silvery-grey transition metal, atomic number 75. One of the rarest elements in Earth crust. Has the second highest melting point after tungsten. Critical compon…
Rhodium
Rhodium is a hard, silvery-white platinum group metal, atomic number 45. One of the rarest and most expensive metals. Key component of catalytic converters in cars. Very high refle…
Roentgenium
Roentgenium is a synthetic radioactive transactinide element named after Wilhelm Röntgen. Expected to behave somewhat similarly to gold. First synthesised in 1994 at GSI Darmstadt.
Rubidium
Rubidium is a soft, silvery-white alkali metal, atomic number 37. Highly reactive - ignites spontaneously in air and reacts explosively with water. Used in atomic clocks and as get…
Ruthenium
Ruthenium is a hard, lustrous, white platinum group metal, atomic number 44. Relatively rare. Used as a hardener in platinum and palladium alloys. Important catalyst in organic che…
Rutherfordium
Rutherfordium is a synthetic radioactive transactinide element named after Ernest Rutherford. It is the first element beyond the actinides and is predicted to behave similarly to h…
Samarium
Samarium is a moderately hard, silvery rare earth metal, atomic number 62. Used in SmCo permanent magnets (samarium cobalt), which retain magnetism at higher temperatures than NdFe…
Scandium
Scandium is a silvery-white transition metal, atomic number 21. Rare in nature despite being the 23rd most abundant element. First member of the transition metals (Period 4, Group …
Seaborgium
Seaborgium is a synthetic radioactive transactinide element named after Glenn T. Seaborg. It is predicted to have properties similar to tungsten. First confirmed synthesis in 1974 …
Selenium
Selenium is a non-metal/metalloid, atomic number 34. An essential trace element for humans and many other organisms (component of selenoproteins, glutathione peroxidase). Has both …
Silicon
Silicon is a lustrous metalloid, atomic number 14, second most abundant element in Earth crust (28%). Pure silicon is a semiconductor - foundation of modern electronics. Forms SiO2…
Silver
Silver is a lustrous, soft, white precious metal, atomic number 47. Has the highest electrical and thermal conductivity of all metals. Used since antiquity for jewellery, currency,…
Sodium
Sodium is a soft, silvery-white alkali metal, atomic number 11. Highly reactive with water. Essential for life - regulates fluid balance and nerve impulses. Sixth most abundant ele…
Strontium
Strontium is a soft, silvery alkaline earth metal, atomic number 38. Named after Strontian, Scotland. Notable for its brilliant crimson flame colour used in fireworks. Radioactive …
Sulfur
Sulfur is a bright yellow non-metal, atomic number 16. Found in nature as elemental deposits and in sulfide/sulfate minerals. Odourless as element. Essential for life as component …