Some nuclei are radioactive—they spontaneously decay destroying some part of their mass and emitting energetic rays, a process called nuclear radioactivity Nuclear radiation, like x rays, is ionizing radiation, because energy sufficient to ionize matter is emitted in each decay

The range (or distance traveled in a material) of ionizing radiation is directly related to the charge of the emitted particle and its energy, with greater-charge and lower-energy particles having the shortest ranges The two types of nucleons are protons and neutrons; they are very similar, except that the proton is positively charged while the neutron is neutral.

radioactivity — the emission of rays from the nuclei of atoms. activity — the rate of decay for radioactive nuclides. two types of nucleons — protons and neutrons; they are very similar, except that the proton is positively charged while the neutron is neutral. radiation detector — a device that is used to detect and track the radiation from a radioactive reaction.