CHEMISTRY GLOSSARY

oxygen    →   kisik

Oxygen was discovered by Joseph Priestley (England) in 1774. The origin of the name comes from the Greek words oxy genes meaning acid and forming (acid former). It is colourless, odourless gas; pale blue liquid. Extremely reactive. Forms oxides with nearly all other elements except noble gases. It is the most abundant element in the earth’s crust and makes up almost 21 % of the atmosphere. Oxygen is obtained primarily from liquid air by fractional distillation. Small amounts are made in the laboratory by electrolysis of water. Used in steel making, welding and supporting life. Naturally occurring ozone (O₃) in the upper atmosphere shields the earth from ultraviolet radiation.

ozone    →   ozon

Ozone is an alotropic form of oxygen. It is an unstable blue gas with a pungent odour. It is a powerful oxidising agent. The gas is made by passing oxygen through a silent electric discharge.

plastic    →   plastika

Plastic is a material that can be shaped by the application of heat or pressure. Most are based on synthetic polymers although some are the product of natural substances (such as cellulose derivatives, but excluding the rubbers.). They are usually light and permanent solids, being also heat and electric isolators. If the materials soften again when reheated, they are said to be thermoplastic. If, after fashioning, they resist further applications of heat, they are said to be thermoset.

polonium    →   polonij

Polonium was discovered by Marie Curie (Poland) in 1898. Named for Poland, native country of Marie Curie. It is silvery-grey, extremely rare, radioactive metal. Soluble in dilute acids. Highly toxic. Severe radiotoxicity. Carcinogen. Polonium occurs in pitchblende. Produced by bombarding bismuth with neutrons. Used in industrial equipment that eliminates static electricity caused by such processes as rolling paper, wire and sheet metal.

practical salinity    →   praktični salinitet

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). When K₁₅ = 1, the Practical Salinity P S is by definition 35. The conductivity of that reference solution is C(35,1568,0) = 42.914 mS/cm = 4.2914 S/m (Siemens per meter). Note that Practical Salinity is a unit-less quantity. Though sometimes convenient, it is technically incorrect to quote Practical Salinity in "psu". When K₁₅ is not unity, S_P and K₁₅ are related by the PSS-78 equation

At a temperature of t₆₈ = 15 °C, R_t is simply K₁₅ and Practical Salinity S_P can be determined from the above equation. For temperatures other than t₆₈ = 15 °C, Practical Salinity S_P is given by the following function of R_t (k = 0.0162)

promethium    →   prometij

Promethium was discovered by J. A. Marinsky, Lawrence Glendenin and Charles D. Coryell (USA) in 1945. Named after Prometheus in Greek mythology, who stole fire from the gods. It is rare earth metal of synthetic origin on the earth, naturally made in stars. Poison. Radiotoxic. Radioactive. Promethium does not occur naturally. Found among fission products of uranium, thorium and plutonium. It has been used as a source of radioactivity for thickness-measuring gages.

qualitative analysis    →   kvalitativna analiza

Qualitative analysis involves determining the nature of a pure unknown compound or the compounds present in a mixture. Qualitative inorganic analysis is used to separate and detect cations and anions in a sample substance. According to their properties, cations are usually classified into six groups. Each group has a common reagent which can be used to separate them from the solution.

radioactive series    →   radioaktivni niz

Radioactive series is a sequence of nuclides formed by successive radioactive decays until a stable decay product, the end product, is formed. A famous example of a radioactive series is the decay of uranium, which through a series of steps decays into stable lead.

radon    →   radon

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.

resistivity    →   električna otpornost

Electrical resistivity, or specific resistance (ρ) is the electric field strength divided by the current density when there is no electromotive force in the conductor. Resistivity is an intrinsic property of a material. Materials with low resistivity are good conductors of electricity and materials with high resistivity are good insulators.

For a conductor of uniform cross section with area A and length L, and whose resistance is R, the resistivity is given by

The SI unit is Ω m.