1.4—The terms: i ‘relative atomic mass’ based on the 12C scale ii ‘relative molecular mass’ and ‘relative formula mass’

Understand the terms: i ‘relative atomic mass’ based on the 12C scale ii ‘relative molecular mass’ and ‘relative formula mass’, including calculating these values from relative atomic masses The term ‘relative formula mass’ should be used for compounds with giant structures. iii ‘molar mass’ as the mass per mole of a substance in g mol⁻¹ iv parts per million (ppm), including gases in the atmosphere.

Use —the terms: i ‘relative atomic mass’ based on the 12c scale ii ‘relative molecular mass’ and ‘relative formula mass’ to connect the rule to the data and decision in the question.

This matters because —the terms: i ‘relative atomic mass’ based on the 12c scale ii ‘relative molecular mass’ and ‘relative formula mass’ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the terms: i ‘relative atomic mass’ based on the 12c scale ii ‘relative molecular mass’ and ‘relative formula mass’ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.