CHEMISTRY GLOSSARY

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.

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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

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elementary reaction    →   elementarna reakcija

Elementary reaction is a reaction that occurs in a single step. Equations for elementary reactions show the actual molecules, atoms, and ions that react on a molecular level.

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fcc    →   fcc

fcc is abbreviation for face-centered cubic lattice.

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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

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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

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metabolism    →   metabolizam

Metabolism is a sum of all chemical and physiological processes by which the body builds and maintains itself. It is a process of building the body’s molecular structures from nutrients (anabolism) and breaking them down for energy (catabolism).

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monochromator    →   monokromator

Monochromator (from the Greek words mono and chroma meaning single and colour) is an optical device based on dispersion of light by one or more prisms or diffraction gratings into its constituent wavelengths, which are utilized in turn.

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Newtonian fluid    →   Newtonski fluid

Newtonian fluid is a fluid whose viscosity does not depend on gradients in flow speed. Gases and low-molecular weight liquids are usually Newtonian fluids.

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oligomer    →   oligomer

Oligomer is a substance consisting of molecules of intermediate relative molecular mass (molecular weight), the structure of which essentially comprises the multiple repetitions of units derived, actually or conceptually, from molecules of low relative molecular mass. In contrast to a polymer, the properties of an oligomer can vary significantly with the removal of one or a few of its units.

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