CHEMISTRY GLOSSARY

Fajans’ rules    →   Fajansova pravila

Fajans’ rules, formulated by American chemist of Polish origin. Kazimierz Fajans (1887-1975), indicating the extent to which an ionic bond has covalent character caused by polarisation of the ions. Covalent character is more likely if:

1. the charge of the ions is high;

2. the positive ion is small or the negative ion is large;

3. the positive ion has an outer electron configuration that is not a noble- gas configuration.

fat    →   mast

Fats are esters of glycerol and long chain carboxylic acids. Fats occur widely in plants and animals as a means of storing food energy, having twice the calorific value of carbohydrates. Fats derived from plants and fish generally have a greater proportion of unsaturated fatty acids than those from mammals. Fats may be either solid or liquid at room temperature, depending on their structure and composition. Unsaturated fats are liquid at room temperature.

Plant oils may be hardened by the addition of hydrogen atoms, converting double bonds to single bonds. This process is known as hydrogenation. Hydrogenated vegetable oils are often present in margarine and other processed foods.

Alkali hydrolysis of fat with sodium hydroxide it gives glycerol and soap (i.e. a mixture of the sodium salts of the fatty acids).

tertiary alcohol    →   tercijarni alkohol

Tertiary alcohols are aliphatic alcohols in which the hydroxyl group (-OH) is attached to a tertiary carbon atom.

thermodynamics    →   termodinamika

Thermodynamics is the scientific study of the interconversion of heat and other forms of energy.

unsaturated hydrocarbon    →   nezasićeni ugljikovodik

Unsaturated hydrocarbons are organic compounds containing double (alkenes) or triple (alkynes) bonds in their molecules.

free radical    →   slobodni radikal

Free radical is a molecular fragment having one or more unpaired electrons, usually short-lived and highly reactive. They can be produced by photolysis or pyrolysis in which a bond is broken without forming ions. In formulas, a free radical is conventionally indicated by a dot (·CH₃, ·SnH₃, ·Cl). Free radicals are known to be formed by ionising radiation and thus play a part in deleterious degradation effects that occur in irradiated tissue. They also act as initiators or intermediates in oxidation, combustion, photolysis, and polymerisation.

fructose    →   fruktoza

Fructose (fruit sugar) is a ketohexose (a six-carbon ketonic sugar), which occurs in sweet fruits and honey. Glucose and fructose have the same molecular formula, C₆H₁₂O₆, but have different structures. Pure, dry fructose is a very sweet, white, odorless, crystalline solid. Fructose is one of the sweetest of all sugars and is combined with glucose to make sucrose, or common table sugar. An older common name for fructose is levulose, after its levorotatory property of rotating plane polarized light to the left (in contrast to glucose which is dextrorotatory). The polysaccharide inulin is a polymer of fructose.

Gauss’ law for electrostatics    →   Gaussov zakon za elektrostatiku

Gauss’ law describes the relation between charge and electric field in static situations, so it is equivalent to Coulomb’s law, which can be derived from Gauss’ law. Gauss’ law states that the net flux of electric field, Φ, through an imaginary closed surface, S, - a Gaussian surface - is equal to the net charge, q, inside that closed surface:

where electric flux Φ through Gaussian surface is given by:

ε₀ is the permittivity constant and dS is a surface element.

VSEPR    →   VSEPR

Valence shell electron pair repulsion theory (VSEPR) is a model that explains the shapes of molecules by assuming that electron pairs arrange themselves around atoms in a way that minimizes electron-electron repulsions.

wavefunction    →   valna funkcija

Wavefunction (Ψ) is a mathematical function that gives the amplitude of a wave as a function of position (and sometimes as a function of time and/or electron spin). Wavefunctions are used in chemistry to represent the behaviour of electrons bound in atoms or molecules.