^{4}\textrm{He}\) When a radioactive atom emits an alpha particle the mass number decreases by four and the atomic number drops by two. Here is the equation for the alpha decay of radon-219 into ...

Certain isotopes are unstable and undergo a process of radioactive decay, slowly and steadily transforming, molecule by molecule, into a different isotope. This rate of decay is constant for a ...

Radioactive decay is a spontaneous and random process. A block of radioactive material will contain many trillions of nuclei and not all nuclei are likely to decay at the same time so it is ...