This interactive simulation allows users to construct atoms by specifying the number of protons, neutrons, and electrons. It visualizes the atomic structure and plots the isotope on a "Band of Stability" graph, providing real-time feedback on the element's identity, mass number, charge, and nuclear stability.

Build atoms to understand mass number, mix isotopes to see its effect on atomic mass, and then test your knowledge. Two dynamic quizzes on identifying isotopes and calculating atomic mass ensure you can apply what you've learned.