A-level Chemistry Definitions questions and answers well illustrated.

A-level Chemistry Definitions questions and
answers well illustrated.




isotopes - ANS.atoms of the same element with different numbers of neutrons

atomic (proton) number - ANS.the number of protons in the nucleus of an atom

mass (nucleon) number - ANS.the number of particles (protons and neutrons) in the
nucleus

ion - ANS.a positively or negatively charged atom or (covalently bonded) group of
atoms (molecular ion)

relative isotopic mass - ANS.the mass of an atom of an isotope compared with one
twelfth of the mass of an atom of carbon-12

relative atomic mass - ANS.the weighted mean mass of an an atom of an element
compared with one twelfth of the mass of an atom of carbon-12

relative molecular mass (Mr) - ANS.the weighted mean mass of a molecule
compared with one twelfth of the mass of an atom of carbon-12

relative formula mass - ANS.is the weighted mean mass of a formula unit compared
with one twelfth of the mass of an atom of carbon-12

amount of substance - ANS.the quantity whose unit is the mole: chemists use
'amount of substance' as a means of counting atoms