CHEMISTRY GLOSSARY

sugar    →   šećer

Sugar is any of a group of water-soluble carbohydrates of relatively low molecular weight and typically having a sweet taste. The group comprises mainly monosaccharides (glucose, fructose, galactose), disaccharides (sucrose, lactose, maltose), and trisaccharides (raffinose). Many monosaccharides and disaccharides fairly commonly found in nature bear names reflecting the source from which they were first isolated. For example, glucose is also known as grape sugar, lactose as milk sugar, and maltose as malt sugar. In everyday usage, the name is often used to refer specifically to sucrose (table sugar, cane sugar, beet sugar).

supercritical fluid chromatography    →   superkritična fluidna kromatografija

Supercritical fluid chromatography (SFC) is a hybrid of gas and liquid chromatography. SFC is of importance because it permits the separation and determination of a group of compounds that are not conveniently handled by either gas or liquid chromatography. These compounds are either nonvolatile or thermally labile so that gas chromatography cannot be used and they do not contain functional groups that make possible detection by liquid chromatography. SFC has been applied to a wide variety of materials including natural prodcuts, drugs, foods, pesticides and herbicides, fossil fuels, explosives and propellants.

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.

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.

tryglyceride    →   triglicerid

Triglyceride is an ester of glycerol and three fatty acids. It is the main constituent of vegetable oil and animal fats. The fatty acids attached to the glycerol can be the same or different. Natural fatty acids found in plants and animals are typically composed only of even numbers of carbon atoms (usually from 16 to 20) due to the way they are bio-synthesized from acetyl CoA.

ununbium    →   ununbij

Ununbium was discovered by S. Hofmann et al. collaboration at the Heavy Ion Research Laboratory (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany in February 1996. The new element has not yet been officially named, but it is known as ununbium, according to the system designated by the IUPAC for naming new elements. It is synthetic radioactive metal. Using the electromagnetic velocity filter SHIP, fusion-like residues of the reaction of ⁷⁰Zn with enriched ²⁰⁸Pb targets were measured. Two chains of localized alpha-emitters were identified as originating with ²⁷⁷112 + ¹n.

ununquadium    →   ununkvadij

The discovery of ununquadium was reported informally in January 1999 following experiments towards the end of December 1998 involving scientists at Dubna (Joint Institute for Nuclear Research) in Russia and the Lawrence Livermore National Laboratory, USA. The new element has not yet been officially named, but it is known as ununquadium, according to the system designated by the IUPAC for naming new elements. It is synthetic radioactive metal. Only few atoms of element 114 (²⁸⁹114) has ever been made (through a nuclear reaction involving fusing a calcium atom with a plutonium atom) isolation of an observable quantity has never been achieved.

unununium    →   unununij

Unununium was discovered by S. Hofmann et al. collaboration at the Heavy Ion Research Laboratory (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany in December 1994. The new element has not yet been officially named, but it is known as unununium, according to the system designated by the IUPAC for naming new elements. It is synthetic radioactive metal. In bombardments of ²⁰⁹Bi targets with ⁶⁴Ni using the velocity selector SHIP facility to discriminate in favor of the fused product, ²⁷²111 + ¹n, three sets of localized alpha-decay chains were observed with position-sensitive detectors.

water hardness    →   tvrdoća vode

Hardness is defined as the concentrations of calcium and magnesium ions expressed in terms of calcium carbonate. These minerals in water can cause some everyday problems. They react with soap and produce a deposit called soap curd that remains on the skin and clothes and, because it is insoluble and sticky, cannot be removed by rinsing.

Hard water may also shorten the life of plumbing and water heaters. When water containing calcium carbonate is heated, a hard scale is formed that can plug pipes and coat heating elements. Scale is also a poor heat conductor. With increased deposits on the unit, heat is not transmitted to the water fast enough and overheating of the metal causes failure. Build-up of deposits will also reduce the efficiency of the heating unit, increasing the cost of fuel.

There are two types of water hardness, temporary and permanent.

Temporary Hardness is due to the bicarbonate ion, HCO₃^-, being present in the water. This type of hardness can be removed by boiling the water to expel the CO₂, as indicated by the following equation:

Permanent hardness is due to calcium and magnesium nitrates, sulphates, and chlorides etc. This type of hardness cannot be eliminated by boiling.

wire mesh    →   azbestna mrežica

Wire mesh (wire gauze) is used for uniform distribution of flame heat in base of a heated body. It is made of a iron wire strands with or without ceramic interior cores.