Chemistry Figures Bohr Model
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Bohr model diagrams of atoms and ions

Bohr Model draws one atom or ion as a nucleus with its electrons as dots on rings. Pick any of the 118 elements and it sets the protons, the neutrons from the mass number, and the electrons on each shell; set a charge and the shells change to that ion’s ground state, so Na⁺ is drawn 2, 8 and Cl⁻ 2, 8, 8. You can also set every count by hand. Nothing is checked, so a wrong model for a “what’s wrong?” question draws exactly as set.

For questions students complete, leave the nucleus blank or draw the rings without electrons. An ion can show its gained electrons in their own color and its lost electrons as empty dashed spots, and can go in square brackets with its charge. Every model with the same number of shells is drawn the same size, so answer choices line up.

What you can set

  • The element and charge, or the protons and neutrons (0 to 200 each) and 1 to 7 shells of up to 32 electrons, set by hand
  • Fill, which sets the neutral atom’s real ground-state shells
  • The nucleus drawn as proton and neutron balls (up to 40 in all), as written counts, or blank
  • Electrons evenly spaced or paired at the four sides as in Lewis structures, or empty rings
  • Gained and lost electrons, and each particle’s color and symbol (such as p⁺, n⁰ and e⁻)
  • A key, n = 1, n = 2… shell labels, brackets for an ion, and a chart title

Copying, printing and sharing

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Example figures

Frequently asked questions

How many electrons go in each shell of a Bohr model?

Fill uses each element’s real ground state. For the first 20 elements that means shells of up to 2, 8, 8 and 2 (potassium is 2, 8, 8, 1). Past calcium the third shell keeps filling after the fourth has started, so iron is 2, 8, 14, 2.

How does it work out the number of neutrons?

From the mass number, the element’s atomic mass rounded to a whole number, minus its atomic number: chlorine’s 35.45 rounds to 35, giving 18 neutrons. For an element with no stable isotope it uses the bracketed mass number on periodic tables, like [98] for technetium. Change the neutron count to draw another isotope.

Can I draw a Bohr model of an ion?

Yes. Set the charge and the shells change to that ion’s ground state. Turn on Gained and lost electrons to mark how it differs from the neutral atom, and Brackets to put it in square brackets with its charge.

Can I make a blank Bohr model for students to fill in?

Yes. Set the nucleus to Blank for a “how many protons?” question, or turn on Empty rings to draw the shells without electrons for students to add them.

Is there an answer key?

Not a separate line. Use the chart title to name the atom, like “Carbon-12”, or leave it off so students identify it.

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