CHEMISTRY GLOSSARY

sigma bond    →   sigma veza

Most single bonds are sigma bonds (σ-bond). In the valence bond theory, a sigma bond is a valence bond that is symmetrical around the imaginary line between the bonded atoms.

silver coulometer    →   srebrni kulometar

Silver coulometer consists of a platinum vessel which acts as a cathode and contains a solution of pure silver nitrate as an electrolyte (c(AgNO₃) = 1 mol/L). A rod of pure silver enclosed in a porous pot acts as the anode. The current density at the anode should not exceed 0.2 Acm^-2. After electrolysis, the electrolyte is taken out and the platinum vessel is washed, dried and weighed. The increase in the weight gives the amount of silver deposited (96500 C of electricity deposits 107.88 g of silver). From the mass of the silver deposited, the coulomb involved in the reaction can be calculated.

simple cubic lattice    →   jednostavna kubična rešetka

Simple or primitive cubic lattice (sc or cubic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a = b = c and interaxial angels α=β=γ=90°.

The simplest crystal structures are those in which there is only a single atom at each lattice point. In the sc structures the spheres fill 52 % of the volume. The number of atoms in a unit cell is one (8×1/8 = 1). This is only one metal (α-polonium) that have the sc lattice.

silver/silver-chloride electrode    →   srebro/srebrov klorid elektroda

Silver/silver-chloride electrode is by far the most common reference type used today because it is simple, inexpensive, very stable and non-toxic. It is mainly used with saturated potassium chloride electrolyte, but can be used with lower concentrations such as 3.5 mol dm^-3 or 1 mol dm^-3 potassium chloride. Silver/silver-chloride electrode is a referent electrode based on the following halfreaction

simple monoclinic lattice    →   jednostavna monoklinska rešetka

Simple or primitive monoclinic lattice (monoclinic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a≠b≠c and interaxial angles α=γ=90°≠β.

simple orthorhombic lattice    →   jednostavna ortorompska rešetka

Simple or primitive orthorhombic lattice (orthorhombic-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a≠b≠c and interaxial angles α=β=γ=90°.

simple tetragonal lattice    →   jednostavna tetragonska rešetka

Simple or primitive tetragonal lattice (tetragonal-P) has one lattice point at the each corner of the unit cell. It has unit cell vectors a=b≠c and interaxial angles α=β=γ=90°.

solid state    →   čvrsto agregatno stanje

Solid state is characterised by a constant shape and volume. Particles are placed very close to one another and have efect one on another with great attraction forces. Solid bodies do not assume the shape of the container in which they are put.

Soxhlet extractor    →   Soxhletov ekstraktor

Soxhlet extractor is a laboratory apparatus designed to extract substances with a low solubility in the extracting solvent. The method described by the German chemist Franz von Soxhlet (1848-1926) in 1879 is the most commonly used example of a semi-continuous method applied to extraction of lipids from foods. In the Soxhlet extractor, the sample soaks in hot solvent that is periodically siphoned off, distilled and returned to the sample. During each cycle, a portion of the non-volatile compound dissolves in the solvent. After many cycles the desired compound is concentrated in the distillation flask. The solvent in the flask is then evaporated and the mass of the remaining lipid is measured.

sp hybrid orbital    →   sp hibridna orbitala

An sp hybrid orbital is an orbital formed by the linear combination of one s and one p orbital of comparable energy (such 2s and 2p orbitals) on a same atom. The two sp hybrid orbitals are aligned in a straight line in opposite direction (bond angles are 180°). The remaining two p orbitals are at right angles to one another and to the line formed by the two sp orbitals.