Ch. 10 Key Terms - University Physics Volume 3 | OpenStax

Skip to Content Go to accessibility page

Key Terms

activity: magnitude of the decay rate for radioactive nuclides

alpha (α) rays: one of the types of rays emitted from the nucleus of an atom as alpha particles

alpha decay: radioactive nuclear decay associated with the emission of an alpha particle

antielectrons: another term for positrons

antineutrino: antiparticle of an electron’s neutrino in $β^{-}$ decay

atomic mass: total mass of the protons, neutrons, and electrons in a single atom

atomic mass unit: unit used to express the mass of an individual nucleus, where $1 u = 1.66054 \times 10^{−27} kg$

atomic nucleus: tightly packed group of nucleons at the center of an atom

atomic number: number of protons in a nucleus

becquerel (Bq): SI unit for the decay rate of a radioactive material, equal to 1 decay/second

beta ( $β$ ) rays: one of the types of rays emitted from the nucleus of an atom as beta particles

beta decay: radioactive nuclear decay associated with the emission of a beta particle

binding energy (BE): energy needed to break a nucleus into its constituent protons and neutrons

binding energy per nucleon (BEN): energy need to remove a nucleon from a nucleus

breeder reactor: reactor that is designed to make plutonium

carbon-14 dating: method to determine the age of formerly living tissue using the ratio $^{14} C/^{12} C$

chart of the nuclides: graph comprising stable and unstable nuclei

critical mass: minimum mass required of a given nuclide in order for self-sustained fission to occur

criticality: condition in which a chain reaction easily becomes self-sustaining

curie (Ci): unit of decay rate, or the activity of 1 g of $^{226} Ra$ , equal to $3.70 \times 10^{10} Bq$

daughter nucleus: nucleus produced by the decay of a parent nucleus

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

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

decay series: series of nuclear decays ending in a stable nucleus

fission: splitting of a nucleus

gamma ( $γ$ ) rays: one of the types of rays emitted from the nucleus of an atom as gamma particles

gamma decay: radioactive nuclear decay associated with the emission of gamma radiation

half-life: time for half of the original nuclei to decay (or half of the original nuclei remain)

high dose: dose of radiation greater than 1 Sv (100 rem)

isotopes: nuclei having the same number of protons but different numbers of neutrons

lifetime: average time that a nucleus exists before decaying

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

low dose: dose of radiation less than 100 mSv (10 rem)

mass defect: difference between the mass of a nucleus and the total mass of its constituent nucleons

mass number: number of nucleons in a nucleus

moderate dose: dose of radiation from 0.1 Sv to 1 Sv (10 to 100 rem)

neutrino: subatomic elementary particle which has no net electric charge

neutron number: number of neutrons in a nucleus

nuclear fusion: process of combining lighter nuclei to make heavier nuclei

nuclear fusion reactor: nuclear reactor that uses the fusion chain to produce energy

nucleons: protons and neutrons found inside the nucleus of an atom

nucleosynthesis: process of fusion by which all elements on Earth are believed to have been created

nuclide: nucleus

parent nucleus: original nucleus before decay

positron: electron with positive charge

positron emission tomography (PET): tomography technique that uses $β^{+}$ emitters and detects the two annihilation $γ$ rays, aiding in source localization

proton-proton chain: combined reactions that fuse hydrogen nuclei to produce He nuclei

radiation dose unit (rad): ionizing energy deposited per kilogram of tissue

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 law: describes the exponential decrease of parent nuclei in a radioactive sample

radioactive tags: special drugs (radiopharmaceuticals) that allow doctors to track movement of other drugs in the body

radioactivity: spontaneous emission of radiation from nuclei

radiopharmaceutical: compound used for medical imaging

radius of a nucleus: radius of a nucleus is defined as $r = r_{0} A^{1 / 3}$

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

sievert (Sv): SI equivalent of the rem

single-photon-emission computed tomography (SPECT): tomography performed with $γ$ -emitting radiopharmaceuticals

strong nuclear force: force that binds nucleons together in the nucleus

transuranic element: element that lies beyond uranium in the periodic table

Order a print copy

Citation/Attribution

Reuse and redistribution of this content in digital or print format:

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's prior written permission.
This book uses the Creative Commons Attribution-NonCommercial-ShareAlike License, which means that you can reuse and modify the material only for noncommercial purposes, must attribute OpenStax, and must distribute any derivative works under the same license.
Any commercial printing of this textbook, including using a local or custom printer, must be approved by OpenStax, and proper citation provided.
OpenStax-copyrighted images, activities, assessments, and similar components of this book are subject to the same licensing – CC-BY-NC-SA. They can be used for noncommercial purposes with attribution. Commercial use requires permission.
Permission requests: Anyone who intends to incorporate this content (including text, images, and other components) into large language models, use it in AI offerings, use it commercially (including in print), and/or has questions about another use case is welcome to complete our reuse request form.

Attribution information

If you are redistributing all or part of this book in a noncommercial print format, then you must include on every physical page the following attribution:
Access for free at https://openstax.org/books/university-physics-volume-3/pages/1-introduction
If you are redistributing all or part of this book in a noncommercial digital format, then for every page that includes OpenStax content, you must license the derivative work under the same CC-BY-NC-SA license as the original, and include on every digital page view the following attribution:
Access for free at https://openstax.org/books/university-physics-volume-3/pages/1-introduction

Citation information

The information below includes the information needed to generate citations in most major styles (APA, MLA, etc.); you must reformat and organize the information as needed to fit the requirements of the style. Use the information below to generate a citation. We recommend using a citation tool such as this one.

Authors: Samuel J. Ling, Jeff Sanny, William Moebs
Publisher/website: OpenStax
Book title: University Physics Volume 3
Publication date: Sep 29, 2016
Location: Houston, Texas
Book URL: https://openstax.org/books/university-physics-volume-3/pages/1-introduction
Section URL: https://openstax.org/books/university-physics-volume-3/pages/10-key-terms

© Jun 11, 2026 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike License. The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo, and Rice University name, and Rice University logo trademarks, or wordmarks are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.