Looking for structured, AP-aligned practice to help students understand atomic mass, isotopes, and weighted averages in AP Chemistry? This AP Chemistry Unit 1.2 resource provides scaffolded problem sets and AP-style free-response questions (FRQs) designed to help students apply the correct mathematical relationship, show their work clearly, and understand how points are earned on assessments. What’s Included✔ Scaffolded problem set focused on isotopic abundance and average atomic mass ✔