CHEMISTRY GLOSSARY

sulfur    →   sumpor

Sulfur has been known since ancient times. The origin of the name comes from the Sanskrit word sulvere meaning sulphur; also from the Latin word sulphurium meaning sulphur. It is pale yellow, odourless, brittle solid, which is insoluble in water but soluble in carbon disulfide. Sulfur is found in pure form and in ores like cinnabar, galena, sphalerite and stibnite. Pure form is obtained from underground deposits by the Frasch process. Used in matches, gunpowder, medicines, rubber and pesticides, dyes and insecticides. Also for making sulfuric acid (H₂SO₄).

superoxide    →   superoksid

Superoxides are binary compounds containing oxygen in the -½ oxidation state. Sodium superoxide (NaO₂) can be prepared with high oxygen pressures, whereas the superoxides of rubidium, potassium, and cesium can be prepared directly by combustion in air. These compounds are yellow to orange paramagnetic solids. Superoxide ion, O₂^-, has an unpaired electron, is not particularly stable, and spontaneously decomposes into peroxide over time.

They are strong oxidising agents that vigorously hydrolyze (react with water) to produce superoxide and oxygen gas.

tantalum    →   tantal

Tantalum was discovered by Anders Ekeberg (Sweden) in 1802. The origin of the name comes from the Greek word Tantalos meaning father of Niobe in Greek mythology, (tantalum is closely related to niobium in the periodic table). It is rare, grey, heavy, hard but ductile, metal with a high melting point. Exposed surfaces form corrosion resistant oxide film. Attacked by HF and fused alkalis. Metal ignites in air. Tantalum always found with niobium. Chiefly occurs in the mineral tantalite. Often used as an economical substitute for platinum. Tantalum pentoxide is used in capacitors and in camera lenses to increase refracting power. It and its alloys are corrosion and wear resistant so it is used to make surgical and dental tools.

technetium    →   tehnecij

Technetium was discovered by Carlo Perrier and Emilio Segre (Italy) in 1937. The origin of the name comes from the Greek word technikos meaning artificial. It is silvery-grey metal. Resists oxidation but tarnishes in moist air and burns in high oxygen environment. First synthetically produced element. Radioactive. Technetium is made first by bombarding molybdenum with deuterons (heavy hydrogen) in a cyclotron. Added to iron in quantities as low as 55 part-per-million transforms the iron into a corrosion-resistant alloy.

tellurium    →   telurij

Tellurium was discovered by Franz Joseph Muller von Reichstein (Romania) in 1782. The origin of the name comes from the Latin word tellus meaning earth. It is silvery-white, brittle semi-metal. Unreactive with water or HCl; dissolves in HNO₃; burns in air or oxygen. Tellurium is obtained as a by-product of copper and lead refining. Used to improve the machining quality of copper and stainless steel products and to colour glass and ceramics. Also in thermoelectric devices. Some is used in the rubber industry and it is a basic ingredient in manufacturing blasting caps.

terbium    →   terbij

Terbium was discovered by Carl Gustaf Mosander (Sweden) in 1843. Named after Ytterby, a village in Sweden. It is soft, ductile, silvery-grey, rare earth metal. Oxidizes slowly in air. Reacts with cold water. Terbium is found with other rare earths in monazite sand. Other sources are xenotime and euxenite, both of which are oxide mixtures that can contain up to 1 % terbium. It is used in modest amounts in special lasers and solid-state devices.

thallium    →   talij

Thallium was discovered by Sir William Crookes (England) in 1861. The origin of the name comes from the Greek word thallos meaning green twig or green shoot. It is soft grey metal that looks like lead. Tarnishes in moist air. Reacts in heated moist air and in acids. Compounds highly toxic by inhalation or ingestion. Cumulative effects. Thallium is found in iron pyrites. Also in crookesite, hutchinsonite and lorandite. Most is recovered from the by-products of lead and zinc refining. Its compounds are used in rat and ant poisons. Also for detecting infrared radiation.

thorium    →   torij

Thorium was discovered by Jöns Jakob Berzelius (Sweden) in 1828. Named after Thor, the mythological Scandinavian god of war. It is heavy, grey, soft, malleable, ductile, radioactive metal. Tarnishes in air; reacts with water. Reacts violently with oxidants. Thorium is found in various minerals like monazite and thorite. Used in making strong alloys. Also in ultraviolet photoelectric cells. It is a common ingredient in high-quality lenses. Bombarded with neutrons make uranium-233, a nuclear fuel.

thulium    →   tulij

Thulium was discovered by Per Theodore Cleve (Sweden) in 1879. Named after Thule, an ancient name for Scandinavia. It is soft, malleable, ductile, silvery metal. Tarnishes in air. Reacts with water. Flammable dust. Thulium is found with other rare earths in the minerals gadolinite, euxenite, xenotime and monazite. Radioactive thulium is used to power portable X-ray machines, eliminating the need for electrical equipment.

tin    →   kositar

Tin has been known since ancient times. The origin of the name comes from the Latin word stannum meaning tin. It is silvery-white, soft, malleable and ductile metal. Exposed surfaces form oxide film. Resists oxygen and water. Dissolves in acids and bases. Organic tin compounds may be highly toxic. Tin is principally found in the ore cassiterite (SnO₂) and stannine (Cu₂FeSnS₄). Used as a coating for steel cans since it is non-toxic and non-corrosive. Also in solder (33 %Sn:67 %Pb), bronze (20 %Sn:80 %Cu) and pewter. Stannous fluoride (SnF₂), a compound of tin and fluorine is used in some toothpaste.