What this calculator does
Effective nuclear charge (Slater's rules) works out net nuclear charge felt by an electron after shielding, using Slater's rules. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaZeff = Z − σ; σ = 0.35×(same-group electrons, or 0.30 for 1s) + 0.85×(n−1 shell electrons) + 1.00×(n−2 and lower shell electrons)
The inputs explained
| Field | What to enter |
|---|---|
| Atomic number Z | A number. Starts at 26. |
| Other electrons in the same group as the chosen one | A number. Starts at 5. |
| Chosen electron is in 1s | Choose from No, Yes. |
| Electrons in the (n−1) shell | A number. Starts at 8. |
| Electrons in (n−2) shells and lower | A number. Starts at 10. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with atomic number z
Every other input is held at the calculator’s starting values while atomic number z varies. Select any row to load that scenario into the calculator.