The strong force is exerted at nuclear scales and dominates the interactions of nucleons.
Possible nuclear reactions are constrained by the law of conservation of nucleon number.
The behavior of the constituent particles of a nuclear reaction are constrained by laws of conservation of energy, energy- mass equivalence, and conservation of momentum.
For all nuclear reactions, mass and energy may be exchanged due to mass-energy equivalence.
Energy may be released in nuclear processes in the form of kinetic energy of the products or as photons.
Nuclear fusion is the process by which two or more smaller nuclei combine to form a larger nucleus and subatomic particles.
Nuclear fission is the process by which the nucleus of an atom splits into two or more smaller nuclei and subatomic particles.
Nuclear fission may occur spontaneously or may require an energy input to occur, depending on the binding energy of the nucleus.
Radioactive decay is the spontaneous fission of an atomic nucleus.
The time at which an individual nucleus undergoes radioactive decay is indeterminable, but decay rates can be described using probability.
The half-life of a radioactive material is the time for half of the initial number of radioactive nuclei to spontaneously decay.
A material’s half-life may be used to predict the number of nuclei remaining in a sample after a period of time, or the age of a material if the initial amount of material is known.
Different unstable elements and isotopes have vastly different half-lives, ranging from fractions of a second to billions of years.