After You Read Mini Glossary
atomic number: the number of protons in an atom of
an element

mass number: the sum of the number of protons and
neutrons in an atom

average atomic mass: the average mass of the element's
isotopes, weighted according to the abundance of each isotope

nuclear decay: a process that occurs when an unstable atomic
nucleus changes into another more stable nucleus by
emitting radiation

ion: an atom that is no longer neutral because it has gained or
lost electrons

radioactive: spontaneously emits radiation
isotope: an atom of the same element that has a different
number of neutrons

1. Review the terms and their definitions in the Mini Glossary. Write a sentence that
explains how to determine the number of neutrons in an isotope that has 6 protons and
a mass number of 13.