Estimate effective nuclear charge with Slater’s rules for occupied subshells of neutral H–U atoms, including a shielding breakdown.
Method, examples and limits
Select a neutral atom from H through U, then choose an occupied subshell. The calculator evaluates S using Slater’s grouping rules and returns Zeff = Z − S, with each screening contribution shown.
For ns/np electrons, other electrons in the same group contribute 0.35 each (0.30 for 1s), electrons in shell n − 1 contribute 0.85, and lower shells contribute 1.00. For nd/nf electrons, other electrons in that subshell contribute 0.35 and electrons in groups to the left contribute 1.00. Outer groups contribute zero.
Sodium’s 3s electron gives S = 8.8 and Zeff = 2.2. This is an empirical neutral-atom screening estimate, not ionic charge, oxidation state or a substitute for a detailed quantum calculation.
Worked learning guide
Slater’s Rules Explained: Calculating Shielding and Effective Nuclear Charge
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Frequently asked questions
Is effective nuclear charge the ionic charge?
No. Slater effective charge describes a selected electron in an approximate screening model.
Which atoms are supported?
Neutral ground-state atoms with atomic numbers 1 through 92, hydrogen to uranium.