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Atom and Ion Particle Count Explorer

Relate atomic number, mass number, ionic charge and proton, neutron and electron counts with periodic-table identification.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

Neutral sodium-23 has eleven protons, twelve neutrons and eleven electrons. Charge +1 would reduce its electron count to ten.

Atomic number = protons; mass number = protons + neutrons; electrons = protons − charge

Worked example

Enter these known values and leave the other values blank.

Atomic number
11
Mass number
23
Charge
0
Number of protons
11
Number of neutrons
12
Number of electrons
11

Assumptions and limitations

  • Particle counts are whole nonnegative integers; an identified element has 1–118 protons. Charge is in elementary-charge units, positive when electrons are missing. These arithmetic identities do not prove that an isotope or ion is stable. The optional constituent-rest-mass sum uses captured proton, neutron and electron masses; it excludes nuclear and electronic binding energy and is not an isotope atomic weight.

Common questions

What limits this estimate?

Particle counts are whole nonnegative integers; an identified element has 1–118 protons. Charge is in elementary-charge units, positive when electrons are missing. These arithmetic identities do not prove that an isotope or ion is stable. The optional constituent-rest-mass sum uses captured proton, neutron and electron masses; it excludes nuclear and electronic binding energy and is not an isotope atomic weight.

How should I enter a different quantity?

Choose the displayed measurement units before entering a value. Clear the unknown field, enter compatible known values, and use the preserved inverse branches where available. One-way estimates and rounded package outputs keep their original direction.

References

Bookify requires whole particle counts and ionic charge and limits element identification to atomic numbers 1–118.

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