Book: Key Terms: Ch. 24

Question 1

activity (𝒜)

Answer 1

aka decay rate. The change in number of nuclei (𝒩) of radioactive sample divided by the change in time (t).

Question 2

alpha (α) decay

Answer 2

A radioactive process in which an alpha particle is emitted from a nucleus.

Question 3

alpha (α) particle

Answer 3

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.

Question 4

background radiation

Answer 4

Natural ionizing radiation, the most important form of which is cosmic radiation.

Question 5

band of stability

Answer 5

The band of stable nuclides that appears on a plot of number of neutrons vs. number of protons for all nuclides.

Question 6

becquerel (Bq)

Answer 6

The SI unit of radioactivity; 1 Bq = 1 d/s (disintegration per second).

Question 7

beta (β) decay

Answer 7

A radioactive change that encompasses any of three specific processes: β⁻ decay, β⁺ emission, or e⁻ capture.

Question 8

β⁻ decay

Answer 8

aka negatron emission. A radioactive process in which a high-speed electron is emitted from a nucleus.

Question 9

beta (β) particle

Answer 9

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.

Question 10

chain reaction

Answer 10

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.

Question 11

critical mass

Answer 11

The minimum mass of a fissionable substance needed to achieve a chain reaction.

Question 12

curie (Ci)

Answer 12

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).

Question 13

decay constant

Answer 13

The rate constant k for radioactive decay.

Question 14

decay (disintegration) series

Answer 14

aka disintegration series. The succession of steps a parent nuclide undergoes as it decays into a stable daughter nuclide.

Question 15

deuteron

Answer 15

Nuclei of the stable hydrogen isotope deuterium, ²H.

Question 16

electron (e⁻) capture (EC)

Answer 16

A type of radioactive decay in which a nucleus draws in an orbital electron, usually one from the lowest energy level, and releases energy.

Question 17

electron volt (eV)

Answer 17

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.

Question 18

fission

Answer 18

The process by which a heavier nucleus splits into two much lighter nuclei, with the release of a large quantity of energy.

Question 19

free radical

Answer 19

A molecular or atomic species with one or more unpaired electrons, which typically make it very reactive.

Question 20

fusion

Answer 20

The process by which light nuclei combine to form a heavier nucleus with the release of energy.

Question 21

gamma (γ) emission

Answer 21

The type of radioactive decay in which gamma rays are emitted from an excited nucleus.

Question 22

gamma ray (γ)

Answer 22

A very high-energy photon.

Question 23

Geiger-Müller counter

Answer 23

An ionization counter that detects radioactive emissions through their ionization of gas atoms within the instrument.

Question 24

gray (Gy)

Answer 24

The SI unit of absorbed radiation dose; 1 Gy = 1 J/kg tissue.

Question 25

half-life (t_1/2)

Answer 25

The time required for half the initial number of nuclei in a sample to decay.

Question 26

ionization

Answer 26

The process by which an atom absorbs energy from a high-energy radioactive particle and loses an electron to become ionized.

Question 27

ionizing radiation

Answer 27

The high-energy radiation from natural and artificial sources that forms ions in a substance by causing electron loss.

Question 28

isotopes

Answer 28

Atoms of a given atomic number (that is, of a specific element) that have different numbers of neutrons and therefore different mass numbers.

Question 29

nuclear binding energy

Answer 29

The energy required to break 1 mol of nuclei of an element into individual nucleons.

Question 30

nuclear transmutation

Answer 30

The induced conversion of one nucleus into another by bombardment with a particle.

Question 31

nucleon

Answer 31

An elementary particle found in the nucleus of an atom; a proton or a neutron.

Question 32

nuclide

Answer 32

A nuclear species with specific numbers of protons and neutrons.

Question 33

particle accelerator

Answer 33

A device used to impart high kinetic energies to nuclear particles.

Question 34

positron (β⁺)

Answer 34

The antiparticle of an electron.

Question 35

positron (β⁺) emission

Answer 35

A type of radioactive decay in which a positron is emitted from a nucleus.

Question 36

radioactivity

Answer 36

The emissions resulting from the spontaneous disintegration of an unstable nucleus.

Question 37

radioisotope

Answer 37

An isotope with an unstable nucleus that decays through radioactive emissions.

Question 38

radioisotopic dating

Answer 38

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.

Question 39

rad (radiation-absorbed dose)

Answer 39

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.

Question 40

reactor core

Answer 40

The part of a nuclear reactor that contains the fuel rods and generates heat from fission.

Question 41

rem (roentgen equivalent for man)

Answer 41

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.

Question 42

scintillation counter

Answer 42

A device used to detect radioactive emissions through their excitation of atoms, which subsequently emit light.

Question 43

sievert (Sv)

Answer 43

The SI unit of human radiation dosage; 1 Sv = 100 rem.

Question 44

stellar nucleosynthesis

Answer 44

The process by which elements are formed in the stars through nuclear fusion.

Question 45

strong force

Answer 45

An attractive force that exists between all nucleons and is many times stronger than the electrostatic repulsive force.

Question 46

tracer

Answer 46

A radioisotope that signals the presence of the species of interest via radioactive emissions.

Question 47

transuranium element

Answer 47

An element with atomic number higher than that of uranium (Z = 92).