CHEMISTRY GLOSSARY

amount concentration    →   količinska koncentracija

Amount concentration (also called molar concentration and in older literature molarity) is the amount of a given substance in a stated unit of a mixture, solution, or ore. The common unit is mole per cubic decimetre (moldm⁻³) or mole per litre (molL^-1) sometimes denoted by M.

The concentration of an atom, ion, or molecule in a solution may be symbolised by the use of square brackets, as [Ca²⁺].

arginine    →   arginin

Arginine is an electrically charged amino acids with basic side chains. It is one of the least frequent amino acids. As a group the charged amino acids are important for making proteins soluble. These residues are generally located on the surface of the protein. Arginine is well designed to bind the phosphate anion, and is often found in the active centers of proteins that bind phosphorylated substrates. As a cation, arginine, as well as lysine, plays a role in maintaining the overall charge balance of a protein. Although arginine is considered an essential amino acid (it must be obtained through the diet), this is true only during the juvenile period in humans.

• Abbreviations: Arg, R
• IUPAC name: 2-amino-5-(diaminomethylideneamino)pentanoic acid
• Molecular formula: C₆H₁₄N₄O₂
• Molecular weight: 174.20 g/mol

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

heat    →   toplina

Heat is a form of energy associated with and proportional to molecular motion. It can be transferred from one body to another by radiation, conduction, or convection.

intermediate    →   intermedijer

Intermediate is a molecular or ionic species that is formed (directly or indirectly) from the reactants and reacts further (directly or indirectly) to form the products of the reaction. It does not accumulate during the course of the reaction.

ion    →   ion

Ion is an atomic or molecular particle having a net electric charge. Positively charged ions are cations, negatively charged ones anions.

aspartic acid    →   asparaginska kiselina

Aspartic acid is an electrically charged amino acids with acidic side chains. As a group the charged amino acids are relatively abundant and are generally located on the surface of the protein. Aspartic acid and glutamic acid play important roles as general acids in enzyme active centers, as well as in maintaining the solubility and ionic character of proteins. Aspartic acid (sometimes referred to as asparate depending on pH) is non-essential in mammals, being produced from oxaloacetate by transamination.

• Abbreviations: Asp, D
• IUPAC name: 2-aminobutanedioic acid
• Molecular formula: C₄H₇NO₄
• Molecular weight: 133.10 g/mol

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.

isomer    →   izomer

Isomers are compounds that have identical molecular formulae but differ in the nature or sequence of bonding of their atoms (structural isomerism) or in the arrangement of their atoms in space (stereoisomerism).

ligand field theory    →   teorija ligandnog polja

Ligand field theory is a description of the structure of crystals containing a transition metal ion surrounded by nonmetallic ions (ligands). It is based on the construction of molecular orbitals involving the d-orbitals of the central metal ion and combinations of atomic orbitals of the ligands.