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CAIE A-Level Chemistry 2.1.2 Relative Atomic, Isotopic and Formula Mass

Practise selecting the correct relative-mass definition and applying isotope abundance or chemical formula data.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • define relative isotopic mass for one isotope without taking an abundance-weighted average
  • define Ar as the weighted mean mass of atoms of an element relative to the unified atomic mass unit
  • use Mr for molecules and relative formula mass for ionic or giant structures by summing constituent Ar values

2.1.2—Atomic mass, Ar, isotopic mass question 1

[Maximum number: 1]

Copper is used in electrical equipment. It has a melting point of 1085∘C1085^{\circ} \mathrm{C}.

The relative isotopic masses and natural abundances of the two isotopes in a sample of copper are shown in Table 1.1.

Table 1.1

Table 1.1

Define relative atomic mass, ArA_{\mathrm{r}}, in terms of the unified atomic mass unit.

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