Atom Builder — Protons and Electrons
Place protons and electrons to build eight neutral-atom counting diagrams.
Loading your game…
How to play
Tap the center to add a proton. Tap a ring to add an electron. Switch to Remove, use Undo or press Backspace to take a particle away. Check the proton number and electron groups against the target. Hint shows counts from the source. These rings are counting diagrams; neutrons, isotopes and ions are not modeled. Source: PubChem periodic table.
What makes an element?
Its atomic number is the number of protons in its nucleus. Change the proton number and the element changes. This collection contains H, C, N, O, F, P, S and Cl.
Why do the rings matter?
The target represents a neutral atom in its ground state. The electron total equals the proton total; its distribution follows the PubChem electron configuration. The rings are counting aids, not a scale drawing. Neutrons and isotopes are omitted.
How do I correct a mistake?
Switch Add to Remove, or use Undo. Enter and Space place a particle in the focused center or ring; Backspace removes one. Hint shows the target counts without changing your diagram. Completed elements stay saved in this browser.
Keep exploring
Favorites and progress stay in this browser. Clearing browser data removes them.