Sections

Key Terms

Key Terms

activity: rate of decay for radioactive nuclides

alpha decay: type of radioactive decay in which an atomic nucleus emits an alpha particle

anger camera: common medical imaging device that uses a scintillator connected to a series of photomultipliers

atomic number: number of protons in a nucleus

becquerel: SI unit for rate of decay of a radioactive material

beta decay: type of radioactive decay in which an atomic nucleus emits a beta particle

carbon-14 dating: radioactive dating technique based on the radioactivity of carbon-14

chain reaction: self-sustaining sequence of events, exemplified by the self-sustaining nature of a fission reaction at critical mass

critical mass: minimum amount necessary for self-sustained fission of a given nuclide

decay constant: quantity that is inversely proportional to the half-life and that is used in the equation for number of nuclei as a function of time

energy-level diagram: a diagram used to analyze the energy levels of electrons in the orbits of an atom

excited state: any state beyond the n = 1 orbital in which the electron stores energy

Fraunhofer lines: black lines shown on an absorption spectrum that show the wavelengths absorbed by a gas

gamma decay: type of radioactive decay in which an atomic nucleus emits a gamma ray

Geiger tube: very common radiation detector that usually gives an audio output

ground state: the n=1 orbital of an electron

half-life: time in which there is a 50 percent chance that a nucleus will decay

Heisenberg uncertainty principle: fundamental limit to the precision with which pairs of quantities such as momentum and position can be measured

hydrogen-like atom: any atom with only a single electron

isotope: nuclei having the same Z and different N’s

liquid drop model: model of the atomic nucleus (useful only to understand some of its features) in which nucleons in a nucleus act like atoms in a drop

mass number: number of nucleons in a nucleus

nuclear fission: reaction in which a nucleus splits

nuclear fusion: reaction in which two nuclei are combined, or fused, to form a larger nucleus

nucleons: particles found inside nuclei

planetary model of the atom: model of the atom that shows electrons orbiting like planets about a Sun-like nucleus

proton-proton cycle: combined reactions $^{1} H +^{1} H \to^{2} H + e^{-} + v_{e} .$ $^{1} H +^{2} H \to^{3} He + γ$ and $^{3} He +^{3} He \to^{4} He +^{1} H +^{1} H$ that begins with hydrogen and ends with helium

rad: amount of ionizing energy deposited per kilogram of tissue

radioactive: substance or object that emits nuclear radiation

radioactive dating: application of radioactive decay in which the age of a material is determined by the amount of radioactivity of a particular type that occurs

radioactive decay: process by which an atomic nucleus of an unstable atom loses mass and energy by emitting ionizing particles

radioactivity: emission of rays from the nuclei of atoms

radiopharmaceutical: compound used for medical imaging

relative biological effectiveness (RBE): number that expresses the relative amount of damage that a fixed amount of ionizing radiation of a given type can inflict on biological tissues

roentgen equivalent man (rem): dose unit more closely related to effects in biological tissue

Rutherford scattering: scattering of alpha particles by gold nuclei in the gold foil experiment

Rydberg constant: a physical constant related to atomic spectra, with an established value of $1.097 \times 10^{7} m^{- 1}$

scintillator: radiation detection method that records light produced when radiation interacts with materials

strong nuclear force: attractive force that holds nucleons together within the nucleus

tagged: having a radioactive substance attached (to a chemical compound)

therapeutic ratio: the ratio of abnormal cells killed to normal cells killed

transmutation: process of changing elemental composition