- existence and size demonstrated using the Rutherford -scattering experiment.
- consists of nucleons (protons and neutrons)
- isotopes of an element share the same number of protons but different number of neutrons.
- nuclear reactions involve two or more reactants.
- represented using the form:
- for a reaction that releases energy, mass-energy of reactants = mass-energy of products + E,
where and m is the mass defect (difference in mass between the products and reactants).
- binding energy is the energy released when the nucleus is formed from its separate protons and neutrons. The same amount of energy is required to break up a nucleus into its constituent nucleons.
- binding energy per nucleon () is an indication of the stability of a nucleus, where B.E .is binding energy and A is the nucleon number. You need to know how to sketch its variation with nucleon number. (The following video explains the shape of the versus A graph and why it peaks at .
- nuclear fission is the disintegration of a heavy nucleus into two lighter nuclei of comparable mass with the emission of neutrons and release of energy.
- nuclear fusion occurs when two light nuclei combine to form a single more massive nucleus, leading to the release of energy.
- The following quantities are always conserved:
- proton number & neutron number
- spontaneous and random emission of radiation from a radioactive nucleus.
- particle - helium nucleus
- particle - electron
- particle - electromagnetic radiation
where A is the rate of disintegration or activity, N is the number of radioactive nuclei and is the decay constant.
where x could represent the activity, number of undecayed particles or received count rate.
- half-life () is the average time taken for half the original number of radioactive nuclei to decay.
- From ,
- You may also use , as shown in the following video.