Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain what isotopes are and why isotopes of one element have the same chemistry. (Guide: “Isotopes”)
- I can describe the main stages of a mass spectrometer (background) and explain why m/z equals the isotope mass for a +1 ion. (Guide: “What a mass spectrometer does”; Practice Q7)
- I can say what the number, position and height of the peaks in a one-element spectrum tell me. (Guide: “Reading a mass spectrum”; Practice Q1)
- I can explain why, for an element with several isotopes, no single atom has the average atomic mass. (Guide: “Common misconceptions”; Practice Q6)
- I can state which kinds of spectra are outside this topic’s assessment (mixtures, molecules, ions that are not +1). (Guide: “What you will and will not be asked”)
Calculation
- I can calculate an average atomic mass from isotope masses and percentage abundances. (Guide: Worked example 1; Practice Q4)
- I can convert peak heights scaled to the tallest peak into percentage abundances, then find the average. (Guide: Worked example 2; Practice Q2, Q6)
- I can find the abundances of two isotopes from an average atomic mass, using x and 1 − x. (Guide: Worked example 3; Practice Q5)
- I can predict the relative height of a peak from the abundances. (Practice Q5(b))
Reasoning
- I can check an average atomic mass: it must lie between the isotope masses, nearest the most abundant one. (Practice Q2, Q3)
- I can identify an element by comparing a spectrum with average atomic masses. (Practice Q3)
- I can use evidence from a spectrum to evaluate a claim about isotopes or average atomic mass. (Practice Q6, Q7)
- I can explain why a sample with an unusual isotope mix has a different average atomic mass from the periodic-table value. (Practice Q7)
All ticked? Move on to Topic 1.3, Elemental Composition of Pure Substances, or return to the course roadmap.