1
Imprecise or incomplete definitions of chemical terms
“Learn and understand the meaning of key terms such as molecule, isotope, empirical formula.”— 1CH0 Paper 2F, June 2023
How to fix: Learn these definitions precisely from the specification: molecule = a group of atoms joined by covalent bonds; isotope = atoms of the same element with the same number of protons but different numbers of neutrons; empirical formula = the simplest whole-number ratio of atoms; relative formula mass = sum of all relative atomic masses in the formula. For 'isotope', never mix up protons (same) and neutrons (different). Write definitions from memory and cross-check against the syllabus before the exam.