What do the numbers mean?Tap the symbol · change the particles
- Lithium-7: 3 protons, 4 neutrons, 3 electrons
- Sodium ion Na⁺: 11 protons, 12 neutrons, 10 electrons
- Chloride ion Cl⁻: 17 protons, 18 neutrons, 18 electrons
- Chlorine-35: 17 protons, 18 neutrons, 17 electrons
- Chlorine-37: 17 protons, 20 neutrons, 17 electrons
- Carbon-14: 6 protons, 8 neutrons, 6 electrons
Tap the top number, the bottom number, the letters or the charge.
Protonssets the element
Neutronssets the mass
Electronssets the charge
neutrons
charge
arrangement
The worked examples:
Where this comes from: isotopes and half-lives from the Live Chart of Nuclides, International Atomic Energy Agency (IAEA), data downloaded 3 October 2026. Abundances are the share of each element’s atoms found in nature. The usual ions are the simple ions met in this course.