10.9: End of Chapter Key Terms

Definition: Nuclear Physics

• Atom: Once thought to be the smallest piece of matter. Composed of protons, neutrons and electrons.
• Electron: A negatively charged fundamental particle that orbits the nucleus of the atom.
• Atomic Nucleus: The center of the atom, containing most of the atom's mass; composed of protons and neutrons.
• Proton: A positively charged particle located in the atom's nucleus.
• Neutron: An uncharged (neutral) particle with about the same mass as the proton, located in the nucleus.
• Nucleon(s): A (collective) term for protons and neutrons in general.
• Isotope: Atoms with the same number of protons, but different numbers of neutrons.
• Empirical Radius Relationship: A way to find the nuclear radius as a function of nucleon number.
• Coulomb Force: A force of attraction or repulsion between charged particles.
• Strong Force, AKA the Strong Nuclear Force: An attractive force between nucleons that counteracts the Coulomb force.
• Radioactive Decay: The spontaneous transformation of one element into another with the emission of radiation.
• Half-Life: The time required for half the atoms in a radioactive sample to decay.
• Decay Constant: A measure of how likely the atom is to undergo radioactive decay. Related to half-life.
• Mean (average) Lifetime: How long (on average) that a particular atom will exist before decaying.
• Mass Defect: The difference in mass between the initial state of the system and the final state of the system.
• Binding Energy: The energy required to disassemble a nucleus.
• Binding Energy per Nucleon: The energy required to remove a single nucleon from the nucleus. A measure of nuclear stability.
• Antiparticle: A particle that has the same mass as another but opposite charge and magnetic moment.
• Alpha Decay/Alpha Particle: A decay mode that emits an alpha particle (\(^{2}_{2} \alpha \)).
• Beta Decay/Beta Particle: A decay mode that emits a beta particle, which is an electron (\(^{\, 0}_{-1} \text {e} \)) or a positron (\(^{\, 0}_{+1} \text {e} \)).
• Gamma Decay: A decay mode that emits a high energy photon.
• Fission: The splitting of a heavy atomic nucleus into two lighter nuclei, releasing energy.
• Liquid Drop Model: Treating the nucleus like a drop of liquid to explain fission by neutron bombardment.
• Fusion: The process of combining two light atomic nuclei to form a heavier nucleus, releasing energy.
• Quarks: Fundamental particles that combine to form everything except electrons.
• Radioimmunoassay: Nuclear medicine technique used to screen for diseases and drugs.
• Radiopharmaceutical: Drug containing radioactive isotope. Used to track blood flow, drug absorption and perform imaging.
• Brachytherapy: The practice of inserting radioactive 'seeds' into the body in order to kill cancer cells.
• Ionizing Radiation: Radioactive decay products that change the structure of molecules in cells by ionizing atoms.
• Radiation Dose/rad: Definition of radiation exposure in terms of energy per kilogram of body mass.
• Relative Biological Effectiveness: A multiplier that affects radiation dose based on the type of radiation involved.
• Roentgen Equivalent Man: A way to estimate effective biological dose; the product of rad and RBE.