CHEMISTRY GLOSSARY

carbine    →   karbin

Carbine is a triatomic modification of carbon non-existent in nature on Earth, found in outer space and comets

carboanhidrase    →   karboanhidraze

Carboanhidrase is an enzyme that catalyzes creation or decomposition of carbonic acid, regulates proportion of carbon dioxide and carbonic acid in the blood plasma.

alkaline earth metal    →   zemnoalkalijski metal

Alkali earth metal is a term that refers to six elements: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These elements make up group 2 of the periodic table of elements. They all exhibit a single oxidation state, +2. They are all light and very reactive. Barium and radium are the most reactive and beryllium is the least.

To denote slightly soluble metal oxides chemists formerly used the term "earth". The oxides of barium, strontium, and calcium resemble alumina (Al₂O₃), a typical "earth", but form alkaline mixtures with water. For this reason barium, strontium, and calcium were called alkaline earth metals. This name has now been extended to include all of the elements of group 2.

allotrope    →   alotrop

Allotropes are the elements which exist in two or more different forms in the same physical state. Allotropes generally differ in physical properties and may also differ in chemical activity.

Diamond, graphite and fullerenes are three allotropes of the element carbon. Graphite is a soft, black, slippery substance; by contrast, diamond is one of the hardest substances known. The different properties of the allotropes arise from their chemical structures. Diamonds typically crystallize in the cubic crystal system and consist of tetrahedrally bonded carbon atoms. Graphite crystallizes in the hexagonal system. In the fullerenes, the carbon atoms taking the form of a hollow sphere, ellipsoid, or tube.

In some cases, the allotropes are stable over a temperature range, with a definite transition point at which one changes into the other. For instance, tin has two allotropes: white (metallic) tin stable above 13.2 °C and grey (nonmetallic) tin stable below 13.2 °C.

The term allotropes may also be used to refer to the molecular forms of an element. Ozone is a chemically active triatomic allotrope of the element oxygen.

allotropy    →   alotropija

Allotropy (Gr. allos, other, and tropos, manner) is the phenomenon of an element existing in two or more physical forms in the same physical state. The difference between the forms involves either crystaline structure (white, red and black phosphorus), the number of atoms in the molecule of a gas (diatomic oxygen and triatomic ozone), or the molecular structure of a liquid (liquid helium an helium II).

In some cases, the allotropes are stable over a temperature range, with a definite transition point at which one changes into the other. For instance, tin has two allotropes: white (metallic) tin stable above 13.2 °C and grey (nonmetallic) tin stable below 13.2 °C. This form allotropy is called enantiotropy. Form of allotropy, in which there is no transition temperature at which the two are in equilibrium, is called monotropy.

Allotropy does not apply to the substance existing in different physical states as, for example, when ice melts and changes from solid ice to liquid water.

Allotropy is generally restricted to describing polymorphic behaviour in elements, while polymorphism may refer to any material having multiple crystal structures.

chemical compound    →   kemijski spoj

Some substance is a compound only if it can be decomposed into two or more different substances by means of a chemical reaction. If two or more substances react, thus creating a new substance, that new substance is called a chemical compound.

aluminate    →   aluminat

Aluminate is a salt formed when aluminium hydroxide or y-alumina is dissolved in solutions of strong bases, such as sodium hydroxide. Aluminates exist in solutions containing the aluminate ion, commonly written [Al(OH)₄]^-. In fact the ion probably is a complex hydrated ion and can be regarded as formed from a hydrated Al³⁺ ion by removal of four hydrogen ions:

Other aluminates and polyaluminates, such as [Al(OH)₆]^3- and [(HO)₃AlOAl(OH)₃]^2-, are also present.

anomer    →   anomer

Anomers are diastereoisomers of cyclic forms of sugars or similar molecules differing in the configuration at the anomeric carbon (C-1 atom of an aldose or the C-2 atom of a 2-ketose). The cyclic forms of carbohydrates can exist in two forms, α- and β- based on the position of the substituent at the anomeric center. Anomer are designated α if the configuration at the anomeric carbon is the same as that at the reference asymmetric carbon in a Fischer projection. If the configuration differs the anomer is designated β. For example, α-D-glucopyranose and β-D-glucopyranose, the two cyclic forms of glucose, are anomers.

autocatalysis    →   autokataliza

Autocatalysis is a reaction in which its product can act as a catalyst. Oxalate oxidation with permanganate in an acid solution is a slow reaction

Mn²⁺-ions catalyse this reaction. When enough Mn²⁺-ions are created, the reaction occurs instantly.

automatic burette    →   automatska bireta

Automatic burette is used for series of tests. It is connected with a bottle which contains the titration solution. The air is pumped into the bottle by a small rubber air pump, created the pressure in the bottle which the rises the solution to the top of burette. When the the burette is full, the valve is released, the pressure in the bottle falls and the burette automatically sets itself to zero. Work with automatic burettes is by far faster and the consumption of standard solution is smaller.