CHEMISTRY GLOSSARY

alkenes    →   alkeni

Alkenes are acyclic branched or unbranched hydrocarbons having one or more double carbon-carbon bonds in their molecules. In the systematic chemical nomenclature, alkene names end in the suffix -ene. The general formula is C_nH_(2n+2)-2x were x is the number of double bonds. Alkenes that have only one double bond form a homologous series: ethene (ethylene), CH₂=CH₂, propene, CH₃CH₂=CH₂, etc. Alkenes typically undergo addition reactions to the double bond.

alkynes    →   alkini

Alkynes (acetylenes) are acyclic branched or unbranched hydrocarbons having one or more triple carbon-carbon bond. In the systematic chemical nomenclature alkyne names end in the suffix -yne. The general formula is C_nH_(2n+2)-4x were x is the number of triple bonds. Alkynes that have only one triple bond form a homologous series: ethyne (acetylene), CH≡CH, propyne, CH₃CH≡CH, etc. Like alkenes, alkynes undergo addition reaction.

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.

Boudouard’s equilibrium    →   Boudouardova ravnoteža

Boudouard’s equilibrium is established when carbon dioxide reacts with carbon. Because of reactions endothermity the temperature increase shifts the reaction rightwards and the temperature reduction leftwards.

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.

asparagine    →   asparagin

Asparagine is neutral amino acids with polar side chains. The polar amino acids are an important class of amino acids since they provide many of the functional groups found in proteins. Asparagine is a common site for attachment of carbohydrates in glycoproteins. In general this is not very reactive residues. Asparagine is amide derivative of aspartic acid. Asparagine is not essential for humans, which means that it can be synthesized from central metabolic pathway intermediates and is not required in the diet.

• Abbreviations: Asn, N
• IUPAC name: 2,4-diamino-4-oxobutanoic acid
• Molecular formula: C₄H₈N₂O₃
• Molecular weight: 132.12 g/mol

butane    →   butan

Butane is a gaseous hydrocarbon C₄H₁₀ obtained from petroleum (refinery gas or by cracking higher hydrocarbons). The fourth member of the alkane series, it has a straight chain of carbon atoms and is isomeric with 2-methylpropane, formerly called isobutene. It can easily be liquefied under pressure and is supplied into cylinders for use as a fuel gas. It is also a raw material for making buta-1, 3-diene for synthetic rubber.

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.

artificial radioactive isotope    →   umjetni radioaktivni izotop

Artificial radioactive isotopes are formed when an atom is bombed with an accelerator or exposing it to slow moving neutrons in a nuclear reactor. In this way isotopes (radionuclides) are obtained which are non-existent in nature because of their unstability and radioactive transition into stable isotopes. Most important radioactive isotopes are:

Radioactive isotope of cobalt is formed when ordinary metal cobalt is bombed with neutrons in a nuclear reactor.

Radioactive isotope of phosphorus is formed when ordinary phosphorus is bombed with deuterons produced in cyclotron.

radioactive isotope of carbon is formed when a nitrogen is bombed with slow moving neutrons in a nuclear reactor. It is mostly used as a radioactive indicator.