PhET Build an Atom Activity Guide

The PhET: Build an Atom Activity Guide is used along with the free Next
Generation PhET Simulation "PhET: Build an Atom". Students learn how to construct atoms of basic elements by adding protons, neutrons, and electrons one at a time. The best part is that students don’t even know they are learning, they just think they are having fun!

The Build an Atom Activity Guide will lead students to experiment with changing the number of protons, neutrons, and electrons and to predict how changing the number of particles effects the element name, charge, and mass. Students will be introduced to concepts of atomic structure, atomic mass, relative atomic mass, ions, stable and unstable isotopes, and atomic models (orbital and electron cloud). Finally, “the Game” will give students a chance to improve their understanding and to demonstrate what they have learned.

This product includes the Build an Atom Activity Guide and Answer Key in PDF format as well as a Getting Started Guide for teachers.


PhET simulations are fun, interactive, research-based simulations of physical phenomena. As students interact with the simulation, they get immediate feedback about the effects of the changes they made. All PhET simulations are freely available from the PhET website (phet.colorado.edu) and are easy to use and incorporate into the classroom. The new Next Generation sims utilize HTML 5 which allows them to run in any modern web browser on most devices including Chromebooks and tablets like the iPad!