CHEMISTRY GLOSSARY

disaccharide    →   disaharid

Disaccharides are compounds in which two monosaccharides are joined by a glycosidic bond. A glycosidic bond to the anomeric carbon can be either α or β. For example, maltose, the disaccharide obtained by enzyme-catalyzed hydrolysis of starch, consists of two D-glucopyranose units joined by a 1,4’-α-glycoside bond. The "prime" superscript indicates that C-4 is not in the same ring as C-1. Unlike the other disaccharides, sucrose is not a reducing sugar and does not exhibit mutarotation because the glycosidic bond is between the anomeric carbon of glucose and the anomeric carbon of fructose.

London’s force    →   Londonova sila

London’s force is an intermolecular attractive force that arises from a cooperative oscillation of electron clouds on a collection of molecules at close range.

maltase    →   maltaza

Maltase is an enzyme that catalyzes the hydrolysis of the disaccharide maltose into two molecules of glucose.

maltose    →   maltoza

Maltose (malt sugar) is a disaccharide which is obtained with hydrolytic decomposition of starch in the presence of enzyme amylase. Maltose is composed of two glucose molecules linked by an α(1→4)-glycosidic linkage. Maltose has an alpha acetal.

dissociation    →   disocijacija

Dissociation is the process by which a chemical combination breaks up into simpler constituents as a result of either added energy (dissociated by heat), or the effect of a solvent on a dissolved polar compound (electrolytic dissociation). It may occur in the gaseous, solid, or liquid state, or in a solution.

An example of dissociation is the reversible reaction of hydrogen iodide at high temperatures

The term dissociation is also applied to ionisation reactions of acids and bases in water. For example

which is often regarded as a straightforward dissociation into ions

dissociation constant    →   konstanta disocijacije

Dissociation constant is a constant whose numerical value depends on the equilibrium between the undissociated and dissociated forms of a molecule. A higher value indicates greater dissociation.

The term dissociation is also applied to ionisation reactions of acids and bases in water. For example

which is often regarded as a straightforward dissociation into ions

The equilibrium constant of such a dissociation is called the acid dissociation constant or acidity constant, given by

The concentration of water [H₂O] can be taken as constant.

Similarly, for a base, the equilibrium

is also a dissociation; with the base dissociation constant or basicity constant, given by

K_a (K_b) is a measure of the strength of the acid (base).

Markovnikov’s rule    →   Markovnikovljevo pravilo

Markovnikov’s rule: when an asymmetrical alkene reacts with a hydrogen halide to give an alkyl halide, the hydrogen adds to the carbon of the alkene that has the greater number of hydrogen substituents, and the halogen to the carbon of the alkene with the fewer number of hydrogen substituents.

mean free path    →   srednji slobodni put

Mean free path is the average distance a gas molecule travels between collisions.

micelle    →   micele

Micelle is an electrically charged colloidal particle, usually organic in nature, composed of aggregates of large molecules, e.g., in soaps and surfactants. For aqueous solutions, the hydrophilic end of the molecule is on the surface of the micelle, while the hydrophobic end (often a hydrocarbon chain) points toward the centre.

electrical double layer    →   električni dvosloj

Electrical double layer is the structure of charge accumulation and charge separation that always occurs at the interface when an electrode is immersed into an electrolyte solution. The excess charge on the electrode surface is compensated by an accumulation of excess ions of the opposite charge in the solution. The amount of charge is a function of the electrode potential. This structure behaves essentially as a capacitor. There are several theoretical models that describe the structure of the double layer. The three most commonly used ones are the Helmholtz model, the Gouy-Chapman model, and the Gouy-Chapman-Stern model.