CHEMISTRY GLOSSARY

carmine    →   karmin

Carmine is a bright crimson red colour gained from a type of plant lice. Its main ingredient is carmine acid, and it is often used in the colouring of cosmetics, medicines, foods.

Beer’s law    →   Beerov zakon

Beer’s law (or Beer-Lambert law) is the functional relationship between the quantity measured in an absorption method (A) and the quantity sought, the analyte concentration (c). As a consequence of interactions between the photons and absorbing particles, the power of the beam is attenuated from P_o to P. Beer’s law can be written

where A is the absorbance at a given wavelength of light, ε is the molar absorbtivity or extinction coefficient (L mol^-1 cm^-1), unique to each molecule and varying with wavelength, b is the length of light path through the sample (cm), and c is the concentration of the compound in solution (mol L^-1).

benzene    →   benzen

Benzene is a colourless liquid hydrocarbon, C₆H₆, b.p. 80 °C. It is now made from petroleum by catalytic reforming (formerly obtained from coal tar). Benzene is the archetypal aromatic compound. It has an unsaturated molecule, yet will not readily undergo addition reactions. On the other hand, it does undergo substitution reactions in which hydrogen atoms are replaced by other atoms or groups.

In 1865, Friedrich August Kekulé purposed the benzene molecule structure as a hexagonal ring which consists of six carbon atoms with alternate carbon-carbon single and carbon-carbon double bond. But such a structure should be highly reactive, and so didn't account for the unreactive nature of benzene. We now know that the best representation for the structure of benzene is indeed, hexagonal, with each C-C bond distance being identical and intermediate between those for a single and double bond. The π-orbitals from each neighbouring carbon atom overlap to form a delocalised molecular orbital which extends around the ring, giving added stability and with it, decreased reactivity. That is the reason the structural formula of benzene represents as a hexagon with a circle in the center which represents the delocalized electrons.

carotenoids    →   karotenoidi

Carotenoids are a group of natural pigments in plants responsible for yellow and orange colours, meltable in fats.

casein    →   kazein

Casein a protein substance found in milk in the form of calcium salt. It is used in industry of plastic masses and synthetic fibres or as an adhesive.

catalase    →   katalaza

Catalase is an enzyme which catalyzes the breakdown of hydrogen peroxide in the body into oxygen and water.

catalytic hydrogenation    →   katalitičko hidrogeniranje

Catalytic hydrogenation is the infusing of unsaturated or impure hydrocarbons with hydrogen gas at controlled temperatures and pressures and in the presence of a catalyst for the purpose of obtaining saturated hydrocarbons and/or removing various impurities such as sulphur and nitrogen.

cation    →   kation

Cation is a positively charged atomic or molecular particle.

beryllium    →   berilij

Beryllium was discovered by Friedrich Wöhler (Germany) and independently by A. B. Bussy (France) in 1828. The origin of the name comes from the Greek word beryllos meaning mineral beryl; also called glucinium from the Greek word glykys meaning sweet. It is steel-grey metal. It resists attack by concentrated nitric acid, has excellent thermal conductivity and is nonmagnetic. At ordinary temperatures, it resists oxidation in air. Beryllium and its salts are toxic and should be handled with the greatest of care. Beryllium is found mostly in minerals like beryl [AlBe₃(Si₆O₁₈)] and chrysoberyl (Al₂BeO₄). Pure beryllium is obtained by chemically reducing beryl mineral. Also by electrolysis of beryllium chloride. Its ability to absorb large amounts of heat makes it useful in spacecraft, missiles, aircraft, etc. Emeralds are beryl crystals with chromium traces giving them their green colour.

beta-glucan    →   beta-glukan

Beta-glucans are are naturally occurring polysaccharides that contain only glucose as structural components, and are linked with β-glycosidic bonds. They is the most known powerful immune stimulant. The most active forms of β-glucans are those comprising D-glucose units with β(1→3) links and with short side-chains of D-glucose attached at the β(1→6) position. These are referred to as beta-1,3/1,6 glucan. They are a major component of soluble dietary fiber, which can be found in cereal grains (oats, barley, wheat), yeast, and certain mushrooms (shiitake, maitake).