The shielding effect can be defined as a reduction in the effective nuclear charge on the electron cloud, due to a difference in the attraction forces on the electrons in the atom.
In hydrogen, or any other atom in group 1A of the periodic table (those with only one valence electron), the force on the electron is just as large as the electromagnetic attraction from the nucleus of the atom.
The shielding theory also contributes to the explanation of why valence-shell electrons are more easily removed from the atom.
Additionally, there is also a shielding effect that occurs between sublevels within the same principal energy level.
As an approximation, we can estimate the effective nuclear charge on each electron by the following: Where Z is the number of protons in the nucleus and
can be found by using quantum chemistry and the Schrödinger equation, or by using Slater's empirical formulas.
In Rutherford backscattering spectroscopy, the correction due to electron screening modifies the Coulomb repulsion between the incident ion and the target nucleus at large distances.