Radon was discovered by Friedrich Ernst Dorn (Germany) in 1900. The origin of the name is variation of the name of element radium; radon was called niton at first, from the Latin word nitens meaning shining. It is colourless, odourless radioactive, heavy, noble gas. Chemically inert and non-flammable. Highly radiotoxic. Carcinogen by inhalation. Radon is formed from the decay of radium in the earths crust. Used to treat some forms of cancer.
Rhenium was discovered by Walter Noddack, Ida Tacke and Otto Berg (Germany) in 1925. The origin of the name comes from the Latin word Rhenus meaning river Rhine. It is rare and costly, dense, silvery-white metal. Tarnishes in moist air. Resists corrosion and oxidation. Dissolves in nitric and sulfuric acids. Has a very high melting point. Rhenium is found in small amounts in gadolinite and molybdenite. Mixed with tungsten or platinum to make filaments for mass spectrographs. Its main value is as a trace alloying agent for hardening metal components that are subjected to continuous frictional forces.
Rhodium was discovered by William Hyde Wollaston (England) in 1804. The origin of the name comes from the Greek word rhodon meaning rose. It is hard, silvery-white metal. Inert in air and acids. Reacts with fused alkalis. Rhodium is obtained as a by-product of nickel production. Used as a coating to prevent wear on high quality science equipment and with platinum to make thermocouples.
Rubidium was discovered by Robert Bunsen and Gustav Kirchhoff (Germany) in 1861. The origin of the name comes from the Latin word rubidius meaning dark red or deepest red. It is soft, silvery-white, highly reactive metal. Ignites in air. Reacts violently with water or oxidants. Rubidium occurs abundantly, but so widespread that production is limited. Usually obtained from lithium production. Used as a catalyst, photocells and vacuum and cathode-ray tubes.
Ruthenium was discovered by Karl Karlovich Klaus (Russia) in 1844. The origin of the name comes from the Latin word Ruthenia meaning Russia. It is rare, extremely brittle, silver-grey metal. Unaffected by air, water or acids. Reacts with very hot (molten) alkalis. Ruthenium is found in pentlandite and pyroxinite. Used to harden platinum and palladium. Aircraft magnetos use platinum alloy with 10 % ruthenium.
Scandium was discovered by Lars Fredrik Nilson (Sweden) in 1879. The origin of the name comes from the Latin word Scandia meaning Scandinavia. It is fairly soft, silvery-white metal. Burns easily. Tarnishes readily in air. Reaction with water releases hydrogen. Reacts with air and halogens. Scandium occurs mainly in the minerals thortveitile (~34 % scandium) and wiikite. Also in some tin and tungsten ores. Pure scandium is obtained as a by-product of uranium refining. Scandium metal is used in some aerospace applications. Scandium oxide (Sc2O2) is used in the manufacture of high-intensity electric lamps. Scandium iodide (ScI3) is used in lamps that produce light having a colour closely matching natural sunlight.
Selenium was discovered by Jöns Jakob Berzelius (Sweden) in 1817. The origin of the name comes from the Greek word selene meaning moon. It is soft metalloid similar to sulfur. Ranges from grey metallic to red glassy appearance. Unaffected by water. Soluble in alkalis and nitric acid. Burns in air. Toxic by inhalation or ingestion. Selenium is obtained from lead, copper and nickel refining. Conducts electricity when struck by light. Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers. Also colours glass red.
Silicon was discovered by Jöns Jacob Berzelius (Sweden) in 1824. The origin of the name comes from the Latin word silicis meaning flint. Amorphous form of silicon is brown powder; crystalline form has grey metallic appearance. Solid form unreactive with oxygen, water and most acids. Dissolves in hot alkali. Silica dust is a moderately toxic acute irritant. Silicon makes up major portion of clay, granite, quartz and sand. Commercial production depends on a reaction between sand (SiO2) and carbon at a temperature of around 2200 °C. Used in glass as silicon dioxide (SiO2). Silicon carbide (SiC) is one of the hardest substances known and used in polishing. Also the crystalline form is used in semiconductors.
Silver has been known since ancient times. The origin of the name comes from the Latin word argentum meaning silver. It is silvery-ductile and malleable metal. Stable in water and oxygen. Reacts with sulfur compounds to form black sulfides. Silver is found in ores called argentite (AgS), light ruby silver (Ag3AsS3), dark ruby silver (Ag3SbS3) and brittle silver. Used in alloys for jewellery and in other compounds for photography. It is also a good conductor, but expensive.
Sodium was discovered by Sir Humphry Davy (England) in 1807. The origin of the name comes from the Latin word natrium meaning sodium carbonate. It is soft silvery-white metal. Fresh surfaces oxidize rapidly. Reacts vigorously, even violently with water. Reacts with water to give off flammable gas. Burns in air with a brilliant white flame. Sodium is obtained by electrolysis of melted sodium chloride (salt), borax and cryolite. Metallic sodium is vital in the manufacture of organic compounds. Sodium chloride (NaCl) is table salt. Liquid sodium is used to cool nuclear reactors.
Generalic, Eni. "Naruhodo meaning." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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Periodic Table