Bohr Model Maker: Draw Atom Diagrams You Can Check

Choose an element in the Bohr Model Maker. Its atomic number sets the proton count and, for a neutral atom, the electron count. Enter the isotope's mass number to get the neutrons, check the dots on each shell, then download the diagram as SVG or PNG.

A Bohr model is a simplified classroom diagram of an atom. It shows the nucleus and groups electrons into shells, so you can count protons, neutrons and the electrons in each shell. The rings stand for energy levels, not the electrons' actual paths.

The first shell holds up to 2 electrons and the second up to 8. Later shells depend on subshell energy order, so the simple 2-8-8 rule works for many introductory examples but not every element. This tool stores ground-state shell counts for neutral elements 1–36, including the chromium and copper exceptions.

Subtract the atomic number from the isotope's mass number to get the neutron count. Oxygen-16 has 8 protons and 8 neutrons; oxygen-18 still has 8 protons but 10 neutrons. Use a whole-number mass number, not the average atomic mass printed on most periodic tables.

After choosing an element from 1–20, set a positive or negative charge. The electron total changes while protons and neutrons stay the same. Neutral sodium has 11 electrons in shells 2, 8, 1; Na⁺ has 10 in shells 2, 8. Ions of elements 21–36 are not supported because transition-metal ions need extra orbital rules.

Turn on Compare with the neutral atom, then change the mass number. The two diagrams appear side by side with proton, neutron, electron and shell counts, and you can download the pair as one SVG or PNG. For neutral isotopes of one element, only the neutron count changes.

The generator and its SVG and PNG downloads work with no account and no watermark. The atom diagram is calculated in your browser, so you can check electron shells, particle totals and isotope or ion changes before saving an image for a worksheet or presentation.

Choose SVG when the diagram must stay sharp at any size or needs editing in a vector app. Choose PNG for documents, classroom slides and worksheets. Both formats download with no account or watermark. Check any publisher or school file requirements before submitting.