Radioactivity

• Describe the atomic structure: positive nucleus surrounded by electrons. • Describe the evolution of atomic models (Dalton, Thomson, Rutherford, Bohr). • Recall the order of magnitude of atomic sizes. • Recall nucleus composition (protons, neutrons) and characteristic positive charge. • Define isotopes as nuclei of the same element with different neutron numbers. • Use standard notation for isotopes. • Recall the emission of alpha, beta, neutrons, and gamma rays from unstable nuclei. • Relate emissions to changes in nuclear mass and charge. • Write balanced equations for radioactive decay. • Explain half-life and the random nature of decay. • Calculate net decline in emission after integral half-lives. • Interpret activity-time graphs to determine half-life.