Define half-life as the time taken for the number of radioactive nuclei in a sample to halve.

Within Half-lives and the random nature of radioactive decay, this learning objective asks you to define half-life as the time taken for the number of radioactive nuclei in a sample to halve. Focus on the approved ideas half-life and connect them clearly to Atoms and nuclear radiation. A strong response should state the relevant particle, radiation, isotope, decay, half-life or nuclear-equation idea, then explain how it answers the exact command word. Avoid swapping nearby concepts such as atomic number and mass number, isotope and ion, alpha, beta and gamma radiation, or contamination and irradiation.