CHEMISTRY GLOSSARY

body-centered cubic lattice    →   prostorno centrirana kubična rešetka

Body-centered cubic lattice (bcc or cubic-I), like all lattices, has lattice points at the eight corners of the unit cell plus an additional points at the center of the cell. It has unit cell vectors a = b = c and interaxial angles α=β=γ=90°.

The simplest crystal structures are those in which there is only a single atom at each lattice point. In the bcc structures the spheres fill 68 % of the volume. The number of atoms in a unit cell is two (8 × 1/8 + 1 = 2). There are 23 metals that have the bcc lattice.

cation    →   kation

Cation is a positively charged atomic or molecular particle.

chain    →   lanac

Chain is a linear combination of the same type of atom in a molecule. In straight chain molecules, the atoms are arranged in a line, with each atom in the chain linked to one preceding atom and one succeeding atom of the same type. A closed chain molecule is a chain where the atoms are linked in a ring structure.

charge number    →   nabojni broj

Charge number represents ion charge of an atom or a group. It is denoted as a right superscript (Fe²⁺ or SO₄^2-).

chelating agent    →   kelatni agens

Chelating agent is ligand that binds to a metal using more than one atom; a polydentate ligand.

chemical element    →   kemijski element

Chemical element is a type of matter of which elementary matter is composed. Chemical element is composed of atoms with the same core charge.

chemical equation equalization    →   izjednačavanje kemijske jednadžbe

Chemical equation equalization is determining values of stechiometric coefficients of reactants and products in a chemical equation in a way that the number of atoms of each element is equal before and after the reaction.

Bohr magneton    →   Bohrov magneton

Bohr magneton (μ_B) is the atomic unit of magnetic moment, defined as

where h is Planck’s constant, m_e the electron mass, and e the elementary charge. It is the moment associated with a single electron spin.

Born-Haber cycle    →   Born-Haberov kružni proces

Born-Haber cycle is a cycle of reactions used for calculating the lattice energies of ionic crystalline solids. For a compound MX, the lattice energy is the enthalpy of the reaction

The standard enthalpy of formation of the ionic solid is the enthalpy of the reaction

The cycle involves equating this enthalpy (which can be measured) to the sum of the enthalpies of a number of steps proceeding from the elements to the ionic solid. The steps are:

1) Atomization of the metal

2) Atomization of the nonmetal

3) Ionisation of the metal

This is obtained from the ionisation potential.

4) Ionisation of the nonmetal

This is electron affinity.

5) Formation of the ionic solids

Equation of the enthalpies gives

from which ΔH_L can be found.

chemical reaction    →   kemijska reakcija

Chemical reaction is a change of chemical properties of substances which react with each other. By means of a chemical reaction new substances are created by bond breaking between atoms and molecules of reactants and their reuniting in a new way, thereby creating products. Chemical reactions can be shown by chemical equations.