Book: Key Terms: Ch. 24 Flashcards
activity (𝒜)
aka decay rate. The change in number of nuclei (𝒩) of radioactive sample divided by the change in time (t).
alpha (α) decay
A radioactive process in which an alpha particle is emitted from a nucleus.
alpha (α) particle
α or {4, 2}He²⁺ is a positively charged particle, identical to a helium-4 nucleus, that is one of the common types of radioactive emissions.
background radiation
Natural ionizing radiation, the most important form of which is cosmic radiation.
band of stability
The band of stable nuclides that appears on a plot of number of neutrons vs. number of protons for all nuclides.
becquerel (Bq)
The SI unit of radioactivity; 1 Bq = 1 d/s (disintegration per second).
beta (β) decay
A radioactive change that encompasses any of three specific processes: β⁻ decay, β⁺ emission, or e⁻ capture.
β⁻ decay
aka negatron emission. A radioactive process in which a high-speed electron is emitted from a nucleus.
beta (β) particle
β, β⁻, {-1, 0}β⁻. a negatively charged particle, identified as a high-speed electron, that is one of the common types of radioactive emissions.
chain reaction
In nuclear fission, a self-sustaining process in which neutrons released by splitting of one nucleus cause other nuclei to split, which releases more neutrons, and so on.
critical mass
The minimum mass of a fissionable substance needed to achieve a chain reaction.
curie (Ci)
The most common unit of radioactivity, originally defined as the number of nuclei disintegrating each second in 1 g of radium-226; now a fixed quantity. 1 Ci = 3.70×10^10 d/s (disintegrations per second).
decay constant
The rate constant k for radioactive decay.
decay (disintegration) series
aka disintegration series. The succession of steps a parent nuclide undergoes as it decays into a stable daughter nuclide.
deuteron
Nuclei of the stable hydrogen isotope deuterium, ²H.
electron (e⁻) capture (EC)
A type of radioactive decay in which a nucleus draws in an orbital electron, usually one from the lowest energy level, and releases energy.
electron volt (eV)
The energy (in joules, J) that an electron acquires when it moves through a potential difference of 1 volt; 1 eV = 1.602×10^-19 J.
fission
The process by which a heavier nucleus splits into two much lighter nuclei, with the release of a large quantity of energy.
free radical
A molecular or atomic species with one or more unpaired electrons, which typically make it very reactive.
fusion
The process by which light nuclei combine to form a heavier nucleus with the release of energy.
gamma (γ) emission
The type of radioactive decay in which gamma rays are emitted from an excited nucleus.
gamma ray (γ)
A very high-energy photon.
Geiger-Müller counter
An ionization counter that detects radioactive emissions through their ionization of gas atoms within the instrument.
gray (Gy)
The SI unit of absorbed radiation dose; 1 Gy = 1 J/kg tissue.
half-life (t_1/2)
The time required for half the initial number of nuclei in a sample to decay.
ionization
The process by which an atom absorbs energy from a high-energy radioactive particle and loses an electron to become ionized.
ionizing radiation
The high-energy radiation from natural and artificial sources that forms ions in a substance by causing electron loss.
isotopes
Atoms of a given atomic number (that is, of a specific element) that have different numbers of neutrons and therefore different mass numbers.
nuclear binding energy
The energy required to break 1 mol of nuclei of an element into individual nucleons.
nuclear transmutation
The induced conversion of one nucleus into another by bombardment with a particle.
nucleon
An elementary particle found in the nucleus of an atom; a proton or a neutron.
nuclide
A nuclear species with specific numbers of protons and neutrons.
particle accelerator
A device used to impart high kinetic energies to nuclear particles.
positron (β⁺)
The antiparticle of an electron.
positron (β⁺) emission
A type of radioactive decay in which a positron is emitted from a nucleus.
radioactivity
The emissions resulting from the spontaneous disintegration of an unstable nucleus.
radioisotope
An isotope with an unstable nucleus that decays through radioactive emissions.
radioisotopic dating
A method for determining the age of an object based on the rate of decay of a particular radioactive nuclide relative to a stable nuclide.
rad (radiation-absorbed dose)
The quantity of radiations that results in 0.01 J of energy being absorbed per kilogram of tissue; 1 rad = 0.01 J/kg tissue = 10^-2 Gy.
reactor core
The part of a nuclear reactor that contains the fuel rods and generates heat from fission.
rem (roentgen equivalent for man)
The unit of radiation dosage for a human based on the product of the number of rads and a factor relating to the biological tissue; 1 rem = 10^-2 Sv.
scintillation counter
A device used to detect radioactive emissions through their excitation of atoms, which subsequently emit light.
sievert (Sv)
The SI unit of human radiation dosage; 1 Sv = 100 rem.
stellar nucleosynthesis
The process by which elements are formed in the stars through nuclear fusion.
strong force
An attractive force that exists between all nucleons and is many times stronger than the electrostatic repulsive force.
tracer
A radioisotope that signals the presence of the species of interest via radioactive emissions.
transuranium element
An element with atomic number higher than that of uranium (Z = 92).
