This GCSE Physics quiz on radioactivity takes a look at radioactive substances. Radioactive substances emit hazardous particles which can damage the structure of materials and molecules including those in our own bodies. It is released as the nucleus of an unstable atom decays, breaking down into new materials. It only happens to unstable isotopes of element, for example, carbon-12 atoms are stable isotopes and their nuclei never change. Carbon-14 is an unstable isotope and sooner or later, its nucleus will change to a nitrogen-14 nucleus by emitting radiation. Radioactive decay is spontaneous, in other words, it happens at random and for no apparent reason.
As time progresses, the level of radioactivity emitted from a sample will drop as the nuclei of the atoms break down into new, more stable isotopes.