Count protons, neutrons, and electrons from Z, A, and ion charge, and show the neutral-atom electron configuration.
| Protons | – |
| Neutrons | – |
| Electrons | – |
| Electron configuration | – |
Use this calculator for first-year atom problems when you know the element and the mass number and need the particle counts, including a simple ion.
Protons = Z, neutrons = A − Z, and electrons = Z − charge (0 for a neutral atom). The configuration is the ground-state Aufbau filling of the neutral atom from Z, with the usual d-block exceptions (Cr, Cu, Mo, Ag, Au). It is a textbook count, not a measured isotope table, and the configuration is not rewritten for the ion.
Atomic number Z: Atomic number from the periodic table, 6 for carbon, 26 for iron.
Mass number A: Protons plus neutrons. For carbon-12 type 12. A cannot be less than Z.
Ion charge: 0 for a neutral atom, 2 for Ca²⁺, −1 for Cl⁻.
Protons, neutrons, electrons: Particle counts for that nuclide and charge.
Electron configuration: Neutral-atom ground-state configuration from Z.
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