CHEMISTRY GLOSSARY

nuclide    →   nuklid

Nuclide is a species of atoms in which each atom has identical atomic number Z and identical mass number A. For example, a carbon-14 (C-14 or ¹⁴C) nuclide is the nucleus of a carbon atom, which has six protons and eight neutrons.

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 This unit superseded both the physical and a chemical mass unit based on oxygen-16 and is sometimes called the unified mass unit or the dalton.

isotone    →   izoton

Isotones are nuclides having the same neutron number N but different atomic number Z.

radioactive series    →   radioaktivni niz

Radioactive series is a sequence of nuclides formed by successive radioactive decays until a stable decay product, the end product, is formed. A famous example of a radioactive series is the decay of uranium, which through a series of steps decays into stable lead.

relative atomic mass    →   relativna atomska masa

Relative atomic mass (A_r) is the ratio of the average mass per atom of the naturally occurring form of an element to 1/12 of the mass of nuclide ¹²C. The term atomic weight is synonymous with the relative atomic mass.

relative molecular mass    →   relativna molekularna masa

Relative molecular mass (M_r) is the ratio of the average mass per molecule or specified entity of a substance to 1/12 of the mass of nuclide ¹²C. Also called molecular weight. It is equal to the sum of the relative atomic masses of all the atoms that comprise a molecule. For example

M_r(H₂SO₄) = 2·A_r(H) + A_r(S) + 4·A_r(O)

= 2·1.0079 + 32.066 + 4·15.999

= 2.0158 + 32.066 + 63.996

= 98.078

unified atomic mass unit    →   unificirana atomska jedinica mase

Unified atomic mass unit (u or m_u) is a unit of mass used in atomic, molecular, and nuclear science, defined as the mass of one atom of ¹²C divided by 12. Its approximate value is