Calcium has an atomic number of 20. Calcium exists as calcium-40, calcium-42, and calcium-44 atoms.
Explain, in terms of protons and neutrons, why these atoms are isotopes of calcium.
87 exam-style questions on Edexcel GCSE Chemistry 2.1 Atomic structure, covering 2.1.1 Development of the atomic model, 2.1.2 Structure of the atom and subatomic particles, 2.1.3 Mass number, isotopes and relative atomic mass, and 2.1.4 Calculating relative atomic mass from isotopic abundance. Each one has a worked solution and a mark scheme showing where the marks go.