What is Nuclear Radiation?
Nuclear radiation is a type of energy radiated (emitted) by certain kinds of matter. We say matter is “radioactive” if its atoms are unstable and decaying by releasing energy as either rays or subatomic particles (pieces of atoms or particles smaller than atoms). At the core of an atom there is the nucleus, this nucleus is made up of protons which have a positive electrical charge, and neutrons which are neutral or have a charge of zero. The outer boundaries or shell of an atom is made of electrons which have a negative charge and can be said to be in motion or constantly changing position. A simplified illustration could be made of electrons orbiting the nucleus like high-speed, little moons, but there’s a lot more to it than that, as physics are very different in the unimaginably tiny subatomic realm than they in our everyday lives, or in astrophysics).
Speaking of astronomy, stars and astronomical events are common sources of the formation of new atoms. Nuclear physics environments created by scientists are another. The basic form of substances is the element. An element is a pure form of matter. All other forms of matter are made of multiple elements, one way or another, but even pure elements have different forms; these are called isotopes. A physicist could have two lumps of uranium that are both pure, elemental uranium, but one lump of uranium is one isotope of uranium (such as U235) and the other lump is a different isotope (such as U238). An element always has the same amount of protons, but what makes different isotopes is a differing number of neutrons in the nuclei.
Since different subatomic particles have different electrical charges, different ratios of them cause the forces atom to always be sort of striving toward equality. This causes atoms that are relatively imbalanced in this manner to be unstable and decay. In this process of remitting atomic radiation, the matter passes through stages where, sooner or later, it becomes either a different isotope or even a different element.