7.4 understand that alpha and beta particles and gamma rays are ionising radiations emitted from unstable nuclei in a random process

Alpha and beta particles and gamma rays are emitted from unstable nuclei (in an attempt to make them more stable), this is known as radioactive decay. Radioactive decay is spontaneous and random, there is no (current) way of detecting when an unstable nucleus will decay and there is no way of speeding up/slowing down the process as it is completely unaffected by physical conditions (such as temperature of pH) or by and sort of chemical reactions/bondings.

NOTE: When a nucleus decays, it emits either alpha particles, beta particles or gamma rays (sometimes more than one kind, e.g alpha and gamma, or beta and alpha).