Relative Atomic, Molecular & Formula Mass | Stoichiometry L1 | AS Chemistry (CIE 9701)

Lesson 1 of Atoms, Molecules & Stoichiometry for Cambridge International AS Level Chemistry (9701). Why chemists use relative masses, and how to work out relative isotopic mass, relative atomic mass (Ar) from mass spectra, relative molecular mass (Mr) and relative formula mass. ⏱️ CHAPTERS 0:00 Introduction 1:50 Why relative mass? 6:31 Isotopic mass 9:14 Relative atomic mass 20:50 Relative molecular mass 25:32 Relative formula mass 34:00 Why it matters 📝 PAST PAPER QUESTIONS 15:11 Relative atomic mass of neon from a mass spectrum with peak abundances (9701/13 O/N 2021 Q1, MCQ) 17:20 Relative atomic mass of lead from an isotope-abundance diagram (9701/12 M/J 2023 Q40, MCQ) 19:29 Define relative atomic mass, with iron's three isotopes as the context (9701/22 M/J 2025 Q2(a)(i), [2]) ▶ Watch the whole Atoms, Molecules & Stoichiometry chapter in order:    • Atoms, Molecules & Stoichiometry | AS Chem...   📘 Full AS Chemistry 9701 course:    • AS Level Chemistry 9701 Full Course | CIE ...   🎓 The entire AS & A Level course is available on https://www.askpapers.com 📚 Practise on AskPapers • Topical past papers → https://www.askpapers.com/topics • Yearly papers + mark schemes → https://www.askpapers.com/papers • Revision notes → https://www.askpapers.com/notes • AI tutor → https://www.askpapers.com/tutor 🔔 Subscribe for full syllabus lessons, most repeated questions and solved past papers for Cambridge AS & A Level Chemistry. #ALevelChemistry #ASChemistry #9701 #CAIE #CIEChemistry #Stoichiometry #RelativeAtomicMass #MassSpectrometry #Chemistry AskPapers is not affiliated with or endorsed by Cambridge University Press & Assessment. Past-paper questions are © UCLES and used for educational commentary.