CHEMISTRY GLOSSARY

iridium    →   iridij

Iridium was discovered by Smithson Tennant (England) in 1803. The origin of the name comes from the Latin word iris, meaning rainbow, because its salts are highly colored. It is heavy, brittle, white metal. Unreactive in air, water and acids. Attacked by fused NaOH. Metal ignites and burns readily. Iridium is found in gravel deposits with platinum. Used with osmium to tip gold pen points, to make crucible and special containers. Also to make alloys used for standard weights and measures and heat-resistant alloys. Also as hardening agent for platinum.

manganese    →   mangan

Manganese was discovered by Johann Gahn (Sweden) in 1774. The origin of the name comes from the Latin word magnes meaning magnet, or magnesia nigri meaning black magnesia (MnO₂). It is hard, brittle, grey-white metal with a pinkish tinge. Impure forms are reactive. Rusts like iron in moist air. Manganese is most abundant ores are pyrolusite (MnO₂), psilomelane [(Ba,H₂O)₂Mn₅O₁₀] and rhodochrosite (MnCO₃). Pure metal produced by mixing MnO₂ with powered Al and ignited in a furnace. Used in steel, batteries and ceramics. The steel in railroad tracks can contain as much as 1.2 % manganese. It is crucial to the effectiveness of vitamin B₁.

Moh’s scale    →   Mohsova skala

Mohs’ scale of mineral hardness characterises the scratch resistance of various minerals through the ability of a harder material to scratch a softer. It was created by the German mineralogist Friedrich Mohs (1773-1839). Mohs based the scale on the ten readily available minerals.

molybdenum    →   molibden

Molybdenum was discovered by Carl William Scheele (Sweden) in 1778. The origin of the name comes from the Greek word molybdos meaning lead. It is silvery white, very hard metal, but is softer and more ductile than tungsten. Molybdenum is found in the minerals molybdenite (MoS₂) and wulfenite (MoO₄Pb). Its alloys are used in aircraft, missiles and protective coatings in boiler plate.

osmium    →   osmij

Osmium was discovered by Smithson Tennant (England) in 1803. The origin of the name comes from the Greek word osme meaning smell. It is hard fine black powder or hard, lustrous, blue-white metal. Unaffected by air, water and acids. Characteristic acrid, chlorine like odour due to tetroxide compound. Osmium tetroxide highly toxic. Osmium is obtained from the same ores as platinum. Used to tip gold pen points, instrument pivots, to make electric light filaments. Used for high temperature alloys and pressure bearings. Very hard and resists corrosion better than any other.

palladium    →   paladij

Palladium was discovered by William Hyde Wollaston (England) in 1803. Named after the asteroid Pallas which was discovered at about the same time and from the Greek name Pallas, goddess of wisdom. It is soft, malleable, ductile, silvery-white metal. Resists corrosion; dissolves in oxidizing acids. Absorbs hydrogen. Metal dust is combustible. Palladium is obtained with platinum, nickel, copper and mercury ores. Used as a substitute for silver in dental items and jewellery. The pure metal is used as the delicate mainsprings in analog wristwatches. Also used in surgical instruments and as catalyst.

rhodium    →   rodij

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.

ruthenium    →   rutenij

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.

titanium    →   titanij

Titanium was discovered by William Gregor (England) in 1791. Named after the Titans, the sons of the Earth goddess in Greek mythology. It is shiny, dark-grey metal. Powdered form burns in air. Exposed surfaces form oxide coating. It can be highly polished and is relatively immune to tarnishing. Unreactive with alkali and most acids. Titanium usually occurs in the minerals ilmenite (FeTiO₃), rutile (TiO₂) and iron ores. Pure metal produced by heating TiO₂ with C and Cl₂ to produce TiCl₄ then heated with Mg gas in Ar atmosphere. Since it is strong and resists acids it is used in many alloys. Titanium dioxide (TiO₂), a white pigment that covers surfaces very well, is used in paint, rubber, paper and many others.

transition metal    →   prijelazni element

This group of metals is distinguished from other metals not by their physical properties, but by their electronic structure. Transition metals are elements characterized by a partially filled d subshell. The First Transition Series comprises scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu). The Second and Third Transition Series include the lanthanides and actinides, respectively.

The transition metals are noted for their variability in oxidation state. Thus, manganese has two electrons in its outside shell and five electrons in the next shell down, and exhibits oxidation states of +1, +2, +3, +4, +5, +6, and +7.

They are also characterised by the fact that well into the series, going from left to right, the properties of the succeeding metals do not differ greatly from the preceding ones.