This document provides definitions and examples to help explain key concepts about electrons and electron configuration. It defines electrons as negatively charged subatomic particles found outside an atom's nucleus that occupy different energy levels. The number of electrons in each energy level follows a mathematical pattern. Elements are arranged on the periodic table based on their number of protons and electrons. Elements in the same group have the same outer electron configuration, which influences their chemical properties such as reactivity and stability. Electron dot diagrams are used to represent an element's electron configuration.