This document outlines a self-paced e-lesson on atomic structure with 6 checkpoints. The learning outcomes are to understand the components of an atom including protons, neutrons, electrons and their relative charges and masses. Students will interpret atomic symbols and define isotopes. They will learn to deduce particle numbers in atoms and ions from proton and nucleon numbers. Finally, students will describe the nuclear model of the atom containing protons and neutrons in the nucleus surrounded by electrons in shells.