Enter the atomic number and shielding constant into the calculator to determine the effective nuclear charge. This calculator can also evaluate any of the variables given the others are known.

## Slater’s Rule Formula

The following formula is used to calculate the effective nuclear charge using Slater’s Rule.

Z* = Z - S

Variables:

- Z* is the effective nuclear charge
- Z is the atomic number (number of protons in the nucleus)
- S is the shielding constant

To calculate the effective nuclear charge, subtract the shielding constant from the atomic number. The shielding constant is determined using Slater’s rules, which assign a value to each electron based on its position in the atom and the repulsion it experiences from other electrons. This accounts for the shielding effect, where the repulsion between electrons reduces the effective nuclear charge. The resulting effective nuclear charge can then be used to predict atomic properties such as ionization energy and atomic radii.

## What is Slater’s Rule?

Slater’s Rule is a set of rules used in quantum chemistry to estimate the effective nuclear charge (the net positive charge experienced by an electron in a multi-electron atom) on an electron. Developed by John C. Slater, these rules provide a method to account for the shielding effect, where the repulsion between electrons in an atom reduces the effective nuclear charge. The rules assign a shielding constant to each electron, which is then used to calculate the effective nuclear charge, helping to predict atomic properties such as ionization energy and atomic radii.

## How to Calculate Slater’s Rule?

The following steps outline how to calculate Slater’s Rule using the formula Z* = Z – S.

- First, determine the value of Z (atomic number).
- Next, determine the value of S (shielding constant).
- Next, substitute the values of Z and S into the formula Z* = Z – S.
- Finally, calculate the value of Z* (effective nuclear charge).
- After calculating the result, check your answer with the calculator above.

**Example Problem:**

Use the following variables as an example problem to test your knowledge.

Z (atomic number) = 17

S (shielding constant) = 10