CHEMISTRY GLOSSARY

gravitational constant    →   gravitacijska konstanta

Gravitational constant (G) is the universal constant in the equation for the gravitational force between two particles

where r is the distance between the particles and m₁ and m₂ are their masses.

Bunsen burner    →   Bunsenov plamenik

Bunsen burner is a standard source of heat in the laboratory. German chemist Roberts Bunsen (1811-1899) improved the burner's design, which had been invented by Faraday, to aid his endeavors in spectroscopy. The Bunsen burner has a vertical metal tube through which a fine jet of fuel gas is directed. Air is drawn in through airholes near the base of the tube and the mixture is ignited and burns at the tube’s upper opening. The flow of this air is controlled by an adjustable collar on the side of the metal tube. When the whole is closed a yellow safety flame is displayed. Where as when the whole is open it displays a power dull blue flame with a faint blue outer flame with a vibrant blue core used u for combustion and hearting. The flame can reach temperatures of 1 500 °C.

chain reaction    →   lančana reakcija

Chain reaction is a reaction done in three steps: initiation in which usually radicals are made which react with other molecules in stage of propagation and, when all reactants are spent, it ends by termination when all available radicals are completely spent.

Nuclear chain reaction refers to a process in which neutrons released in fission produce an additional fission in at least one further nucleus. Nuclear power plants operate by precisely controlling the rate at which nuclear reactions occur. On the other hand, nuclear weapons are specifically engineered to produce a reaction that is so fast and intense it cannot be controlled after it has started.

heat of combustion    →   toplina izgaranja

Heat of combustion or enthalpy of combustion is the heat evolved when a definite quantity of a substance is completely oxidised (burned).

heat of fusion    →   toplina taljenja

Heat of fusion or enthalpy of fusion is the heat required to convert a substance from the solid to the liquid state with no temperature change (also called latent heat of fusion or melting).

Heisenberg uncertainty principle    →   Heisenbergov princip neodređenosti

Heisenberg uncertainty principle is the principle that it is not possible to know with unlimited accuracy both the position and momentum of a particle. The German physicist Werner Heisenberg (1901-1976) discovered this principle in 1927.

Charles’ law    →   Charlesov zakon

The volume of a fixed mass of gas at a constant pressure expand by the constant fraction of its volume at 0 °C. For each Celsius or kelvin degree its temperature is raised. For any ideal gas fraction it is approximately 1/273. This can be expressed by the equation

were V° is the volume at 0°C and V is its volume at t°C.

This is equivalent to the statement that the volume of a fixed mass of gas at a constant pressure is proportional to its thermodynamic temperature

This law also know as Gay-Lussac’s law.

An equation similar to the one given above applies to pressures for ideal gases:

intermediate    →   intermedijer

Intermediate is a molecular or ionic species that is formed (directly or indirectly) from the reactants and reacts further (directly or indirectly) to form the products of the reaction. It does not accumulate during the course of the reaction.

lanthanides contraction    →   kontrakcija lantanoida

Lanthanides contraction is a reduction of metal and ion diameters from lanthanum to lutetium and it is caused by a core charge growth inside the same shell. Elements which in the periodic system of elements come after lanthanides have, because of lanthanides contraction, smaller diameter than they should have according to their position in the periodic system of elements.

lattice energy    →   energija kristalne rešetke

Lattice energy is the energy per ion pair required to separate completely the ions in a crystal lattice at a temperature of absolute zero.