CHEMISTRY GLOSSARY

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.

polarography    →   polarografija

Polarography is a volumetric technique which is based on a diffusion controlled analyte travel to the surface of dropping mercury electrode (DME). The surface of the working electrode (dropping mercury electrode) is constantly renewed under dropping conditions and, thus, the conditions under which reaction takes place are readily reproducible. Depolarisation potential enables identification of ions present in the solution, and by measuring the diffusion current their concentration is calculated. Polarography was discovered in 1922 by the Czech chemist Jaroslav Heyrovský (1890-1967).

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.

salinity    →   salinitet

Salinity (S) is a measure of the quantity of dissolved salts in seawater. It is formally defined as the total amount of dissolved solids in seawater in parts per thousand (‰) by weight when all the carbonate has been converted to oxide, the bromide and iodide to chloride, and all organic matter is completely oxidized.

Chlorinity is the oldest of the salinity measures considered and is still a corner-stone in the study of dissolved material in seawater. Based on the principle of constant relative proportions it provides a measure of the total amount of dissolved material in seawater in terms of the concentration of halides. The relationship between chlorinity (Cl) and salinity as set forth in Knudsen’s tables is

In 1962, however, a better expression for the relationship between total dissolved salts and chlorinity was found to be

Practical Salinity (S_P) was introduced as a replacement for Chlorinity. Practical Salinity is is relatively easy to measure using standard conductometers, measurements are more precise and less time consuming than measurements of Chlorinity and accurate measurements can even be made in situ. Practical salinity S_P is defined on the Practical Salinity Scale of 1978 (PSS-78) in terms of the conductivity ratio K₁₅ which is the electrical conductivity of the sample at temperature t₆₈ = 15 °C and pressure equal to one standard atmosphere, divided by the conductivity of a standard potassium chloride (KCl) solution at the same temperature and pressure. The mass fraction of KCl in the standard solution is 0.0324356 (32.4356 g of KCl in 1 kg of solution).

Note that Practical Salinity is a unit-less quantity. Though sometimes convenient, it is technically incorrect to quote Practical Salinity in "psu". For most purposes one can assume that the psu and the ‰, are synonymous.

The global average salinity of ocean waters is about 35 ‰, that is, about 35 g of solid substances are dissolved in 1 kg of seawater.

solid state    →   čvrsto agregatno stanje

Solid state is characterised by a constant shape and volume. Particles are placed very close to one another and have efect one on another with great attraction forces. Solid bodies do not assume the shape of the container in which they are put.

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.

Torricelli, Evangelista    →   Torricelli, Evangelista

Evangelista Torricelli (1852-1908) is Italian physicist and mathematician. He became the first scientist to create a sustained vacuum and to discover the principle of a barometer. He filled a tube three feet long, and hermetically closed at one end, with mercury and set it vertically with the open end in a basin of mercury, taking care that no air-bubbles should get into the tube. The column of mercury invariably fell to about twenty-eight inches, leaving an empty space above its level. He discovered that the variation of the height of the mercury from day to day was caused by changes in the atmospheric pressure. He also constructed a number of large objectives and small, short focus, simple microscopes.

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.