# How Do You Calculate Effective Nuclear Charge?

Effective nuclear charge refers to the charge felt by the outermost (valence) electrons of a multi-electron atom after taking into account the number of shielding electrons that surround the nucleus. The formula for calculating the effective nuclear charge for a single electron is “Z* = Z – S”, where Z* is the effective nuclear charge, Z is the number of protons in the nucleus, and S is the average amount of electron density between the nucleus and the electron for which you are solving. As an example, you can use this formula to find the effective nuclear charge for an electron in lithium, specifically the “2s” electron. Determine the value of Z. Z is the number of protons in the nucleus of the atom, which determines the nucleus’s positive charge. The number of protons in the nucleus of an atom is also known as the atomic number, which can be found on the periodic table of elements. In the example, the value of Z for lithium is 3. Find the value of S by using Slater’s Rules, which pro