CHEMISTRY GLOSSARY

ageing    →   starenje

Ageing is the physical and/or chemical change of a material with respect to time, under defined environmental conditions, leading to improvement or deterioration of properties.

AMU    →   AMU

AMU or atomic mass unit is a unit of mass used to express relative atomic masses. It is equal to 1/12 of the mass of an atom of the isotope carbon-12 and is equal to 1.66 033×10^-27 kg. This unit superseded both the physical and a chemical mass unit based on oxygen-16 and is sometimes called the unified mass unit or the dalton.

astronomical unit    →   astronomska jedinica

Astronomical unit (AU) is a unit of length employed in astronomy for describing planetary distance. It is the mean distance of the earth from the sun, equal to 1.49597870×10¹¹ m.

atomic clock    →   atomski sat

Atomic clock is an apparatus for standardizing time based on periodic phenomena within atoms or molecules (ammonia clock; caesium clock).

alpaca    →   alpaka

Alpaca (alpaka) or Nickel Silver is the generic name for any of a range of non-precious bright silvery-grey metal alloys, composed of copper, nickel and zinc. Despite its name it contains no real silver. It is also commonly called German Silver.

There are many different formulations of alloys which fall within the general term of Nickel Silver. All contain copper, nickel and zinc, while some formulations may additionally include antimony, tin, lead or cadmium. A representative formulation is 65 % copper, 18 % nickel, 17 % zinc. Nickel Silver is widely used for the commercial production of industrial components, housewares, flatware and cutlery, and as the metal substrate for silver-plated goods.

ampere    →   amper

Ampere (A) is the SI base unit of electric current.

The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2×10^-7 newton per metre of length.

angular acceleration    →   kutna akceleracija

If the angular velocity of a body changes from an initial value ω_i to a final value ω_f, average angular acceleration, α, can be defined for the time interval Δt = t_f - t_i:

The instantaneous angular acceleration, α, is the limit of the average angular acceleration, as Δt is made to approach zero:

SI unit for angular acceleration is s^-2.

average rate of reaction    →   prosječna brzina reakcije

Average rate of reaction is calculated in a way that a total change of reactants and products concentration is divided with time which is needed for reaction to end.

Avogadro constant    →   Avogadrova konstanta

Avogadro constant (N_A or L) is the number of elementary entities in one mole of a substance.

It has the value (6.022 045±0.000 031)×10²³ mol^-1.

becquerel    →   bekerel

Becquerel (Bq) is the SI derived unit, with a special name, for radioactivity, equal to s^-1. It describes a radioactivity of an amount of radionuclide decaying at the rate, on average, of one spontaneous nuclear transition per second. The unit was named after the French scientist Antoine Henri Becquerel (1852-1908) (disintegrations per unit time), equal to s^-1.