CHEMISTRY GLOSSARY

reaction mechanism    →   reakcijski mehanizam

Reaction mechanism is a list of all elementary reactions that occur in the course of an overall chemical reaction.

sand    →   pijesak

Sand is loose particles of hard, broken rock or minerals, with a diameter of between 0.02 mm and 2 mm. Sand is the most common form of silica used in making glass.

manganese    →   mangan

Manganese was discovered by Johann Gahn (Sweden) in 1774. The origin of the name comes from the Latin word magnes meaning magnet, or magnesia nigri meaning black magnesia (MnO₂). It is hard, brittle, grey-white metal with a pinkish tinge. Impure forms are reactive. Rusts like iron in moist air. Manganese is most abundant ores are pyrolusite (MnO₂), psilomelane [(Ba,H₂O)₂Mn₅O₁₀] and rhodochrosite (MnCO₃). Pure metal produced by mixing MnO₂ with powered Al and ignited in a furnace. Used in steel, batteries and ceramics. The steel in railroad tracks can contain as much as 1.2 % manganese. It is crucial to the effectiveness of vitamin B₁.

mass    →   masa

Mass (m) is the quantity of matter contained in a particle or body regardless of its location in the universe. Mass is constant, whereas weight is affected by the distance of a body from the centre of the Earth (or of other planet). The SI unit is kilogram.

According to the Einstein equation

all forms of energy possess a mass equivalent.

oxidation number    →   oksidacijski broj

Atoms can give one or more electrons for bond forming. The valence of any atom, which comes from stechiometrical relation of interbonded atoms, is called an oxidation number or an oxidation degree. Oxidation number of atoms in elementary state is zero. An atom of greater electronegativity has a negative, and an atom of lesser electronegativity has a positive oxidation number.

sand filtration    →   pješčana filtracija

Sand filtration is a frequently used and very robust method of removing suspended solids from water. The filtration medium consists of a multiple layer of sand with a variety in size and specific gravity. Sand filters can be supplied in different sizes and materials, both hand operated and fully automatically.

semi-permeable membrane    →   polupropusna membrana

Semi-permeable membrane is a membrane through which only some sorts of particles can pass, while others cannot.

size of the nucleus    →   veličina jezgre

Size of the nucleus was measured by Lord Rutherford using the scattering patterns of alpha particles passing through a gold foil. It is 10^-15 m.

smog    →   smog

Smog is a mixture of smoke and fog. The term is used to describe city fogs in which there is a large proportion of particulate matter (tiny pieces of carbon from exhausts) and also a high concentration of sulphur and nitrogen gases.

Tyndall’s effect    →   Tyndallov efekt

Tyndall’s effect occurs when light disperses on colloid particles. This phenomenon can be seen when a ray of light enters in dark room through a small hole. In the beam some dust particles of colloid dimensions can be seen sparkling.