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.

contaminant    →   kontaminat

Contaminants are any physical, chemical, biological, or radiological substance or matter in water that may be harmful to human health or which degrade the palatability of water.

crystal water    →   kristalna voda

Crystal water is water contained in certain salt crystals. It can be removed by heating. Crystals that contain crystal water are called hydrated and their salts hydrates.

cyanogen    →   cijan

Cyanogen is a colourless gas, (CN)₂ with a pungent odour. The compound is very toxic. It my be prepared in the laboratory by heating mercury (II) cyanide.

cycloalkanes    →   cikloalkani

Cycloalkanes are cyclic saturated hydrocarbons containing a ring of carbon atoms joined by single bonds. They have the general formula C_nH_2n, for example cyclohexane, C₆H₁₂. In general, they behave like the alkanes but are rather less reactive.

dehydrogenation    →   dehidrogenacija

Dehydrogenation is a chemical reaction in which hydrogen is removed from a compound. Dehydrogenation of organic compounds converts single carbon-carbon bonds into double bonds. It is usually affected by means of a metal catalyst or in biological systems by enzyme dehydrogenases.

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.

bomb calorimeter    →   kalorimetrijska bomba

Bomb calorimeter is a type of constant-volume calorimeter used in measuring the heat of combustion of samples which can be burned in oxygen. Four essential parts are required in any bomb calorimeter:

1. a bomb or vessel in which the combustible charges can be burned,
2. a bucket or container for holding the bomb in a measured quantity of water, together with a stirring mechanism,
3. an insulating jacket to protect the bucket from transient thermal stresses during the combustion process, and
4. a thermometer or other sensor for measuring temperature changes within the bucket.

brass    →   mjed

Brasses are alloys of copper and zinc (generally 5 % to 40 %). Brass has been known to man since prehistoric times, long before zinc itself was discovered. It was produced by melting copper together with calamine, a zinc ore. Its ductility reaches a maximum with about 30 % zinc and its tensile strength with 45 % although this property varies greatly with the mechanical and heat treatment of the alloy. Typical applications included gears, plumbing ware fittings, adapters, valves and screw machine products. The French horn is a valved brass wind instrument.

Brass may contain small amounts of other alloying elements, such as aluminum, lead, tin, or nickel. Lead can be added as an alloying element resulting in a brass that can be rapidly machined and produces minimal tool wear. Additions of aluminium, iron and manganese to brass improve strength, whilst silicon additions improve wear resistance. Brass containing tin (< 2 % ) is less liable to corrosion in seawater; it is sometimes called naval brass and is used in naval construction.

dienes    →   dieni

Dienes are unsaturated organic compounds that contain two fixed double bonds between carbon atoms. Dienes in which the two double-bond units are linked by one single bond are termed conjugated.