Bohr atomic model and mini periodic table (Z = 1–20)
Integrated ScienceAtoms, Elements & BondingAges 12–13
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Atoms, Elements & Bonding
Pick the atomic number Z with the ± buttons or by tapping a cell in the mini periodic table. The simulation draws a nucleus of protons and neutrons with electrons orbiting in shells following the Bohr model (shell 1 holds up to 2e, shell 2 up to 8e, shell 3 up to 8e). Students see that protons = electrons = Z, atomic mass ≈ protons + neutrons (amu), the number of shells equals the period number, the number of outer-shell electrons equals the group A number, and the matching cell/period/group is highlighted on the table.
Lesson: Atoms; Chemical elements; Introduction to the periodic table of elements
What it shows
In the Bohr model, electrons move in shells around a tiny nucleus of protons and neutrons. A neutral atom has as many electrons as protons, equal to the atomic number Z, and its mass in atomic mass units is roughly protons plus neutrons. For the first 20 elements the shells fill as 2, 8, 8, and a fourth shell begins at potassium. The number of occupied shells matches the period, and the number of outer-shell electrons matches the main-group number, which is why elements in the same column react in similar ways.
How to use
Step through Z with the ± buttons or tap cells in the mini periodic table, asking students to predict the electron arrangement before it appears. Keep Label electron count per shell on to read the configuration, and switch on Show neutrons in the nucleus when discussing mass. Compare Ne with Na to see a new shell start, then Li, Na and K to see one outer electron in each. Pause freezes the electrons for a clear picture.
Parameters you can change
- Atomic number Z 1–20
- Show neutrons in the nucleus
- Show mini periodic table
- Electron orbit speed 0–3
- Label electron count per shell
Questions to explore
- How many shells does magnesium (Z = 12) have, and how many electrons are in its outer shell?
- What do lithium, sodium and potassium have in common in their electron arrangements?
- Why are neon and argon in the same column, and why do they hardly react with other elements?
