Isotopes Explained | Atomic Structure L3 | AS Chemistry (CIE 9701)

Lesson 3 of Atomic Structure for Cambridge International AS Level Chemistry (9701). What isotopes are, how they affect relative atomic mass (Ar), and how to read and work backwards from mass spectra. ⏱️ CHAPTERS 0:00 Introduction 1:23 What are isotopes? 5:08 Chemical & physical properties 9:04 Relative atomic mass 13:01 Calculating Ar 16:41 Mass spectra 20:32 Working backwards 24:47 Recap 📝 PAST PAPER QUESTIONS 18:16 A sample of iron was analysed in a mass spectrometer. Use its mass spectrum to calculate the relative atomic mass of iron to one decimal place. [2] (2025) 20:51 A sample of iron contains three isotopes and has Ar = 55.8. Given the masses and abundances of two of them, calculate the relative isotopic mass of the third isotope. [2] (2025) ▶ Watch the whole Atomic Structure chapter in order:    • Atomic Structure | AS Chemistry 9701 (CIE)...   📘 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 #AtomicStructure #Isotopes #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.