Effective nuclear charge

Under the nuclear charge is understood in physics and chemistry, the charge of an atomic nucleus.

In Coulomb terms:

With

• The number n of protons in the nucleus and
• E the elementary charge

Most of the nuclear charge, however, given as a non-dimensional atomic number. Then it corresponds to the atomic number, and thus determines to which chemical element it is. Moreover, it is - in the basic, non- ionized state of the subject material - equal to the number of electrons.

Effective nuclear charge

In atoms with several electrons, not all electrons are equally attracted to the nucleus: close to the core electrons shield the positive charge from the outside, so that nuclear distant electrons only experience less attraction by the nucleus. This shielding is taken into account by the effective nuclear charge:

To the shielding constant S by the Slater rules.

The effective nuclear charge depends on the element and the electron configuration. Just as the nuclear charge it is usually reported as dimensionless effective nuclear charge number. It is important to understand the ionization of atoms.