# What is Effective Nuclear Charge?

The inner shell electrons of an atom shield the nucleus, reducing the effect of its positive charge. The parameter known as the effective nuclear charge quantifies this shielding phenomenon.

ScienceStruck Staff

Definition

*It is defined as the effective positive charge felt by an electron in the outer shells of an atom, due to the screening effect of electrons in the inner shells.*The electrons in an atom are distributed in concentric shells around the nuclear center. The attraction felt by outermost electrons, because of the positive nuclear charge, is lessened by the repulsive force exerted by inner shell electrons. It is the result of subtraction of average number of inner shell electrons, from the total atomic number. The calculation formula is the following.

Effective Nuclear Charge (

*Z*) = Z - N_{eff}*valence*) electrons of an atom or an ion, see the inner nuclear charge to be lesser than what it actually is. The consideration of effective nuclear charge makes approximate analytical solutions for multielectron atoms possible.

Calculation Method

^{2}2 s

^{2}2 p

^{2}. Since Z = 6 and N = 2, a valence electron in the 'p' shell will have an effective nuclear charge of '6 - 2', which is equal to 4.