The key difference between effective nuclear charge and shielding effect is that effective nuclear charge is the attractive positive charge of nuclear protons acting on valence electrons, whereas shielding effect is a reduction in the effective nuclear charge on the electron cloud that forms due to a difference in the attraction forces on the electrons in the atom.
Effective nuclear charge and shielding effect are related to each other. Shielding effect refers to core electrons repelling the outer electrons, lowering the effective nuclear charge of the nucleus on the outer electrons.
CONTENTS
1. Overview and Key Difference
2. What is Effective Nuclear Charge
3. What is Shielding Effect
4. Effective Nuclear Charge vs Shielding Effect in Tabular Form
5. Summary – Effective Nuclear Charge vs Shielding Effect
What is Effective Nuclear Charge?
Effective nuclear charge can be described as the actual amount of positive charge experienced by an electron in a multi-electron atom. We use the term “effective” because the shielding effect of negatively charged electrons can prevent the high-energy electrons from experiencing the full nuclear charge of the nucleus. This happens due to the repelling effect of the inner layer.
Moreover, the effective nuclear charge that is experienced by an electron is named the core charge. We can usually determine the strength of the nuclear charge using the oxidation number of the atom. Most of the physical and chemical properties of chemical elements can be explained depending on the electronic configuration.
Figure 01: Effective Nuclear Charge
Typically, the magnitude of ionization potential is based on the size of the atom, nuclear charge, screening effect of the inner shells, and the extent to which the outmost electron penetrates into the charge that could be set up by the inner electron.
Effective atomic number or Zeff is another term associated with effective nuclear charge. This is sometimes known as the effective nuclear charge as well. It is the number of protons an electron sees due to the screening by inner-shell electrons. We can describe it as a measurement of the electrostatic interaction between the negatively charged electrons and positively charged protons in the atom.
Generally, an electron in an atom having only that electron experiences the full charge of the positive nucleus, and we can calculate the effective nuclear charge using Coulomb’s law.
What is Shielding Effect?
Shielding effect is the reduction in the attraction force between electrons and the atomic nucleus in an atom, which reduces the effective nuclear charge. The synonyms for this term are atomic shielding and electron shielding. It describes the attraction between electrons and atomic nuclei in atoms containing more than one electron. Therefore, it is a special case of electron-field screening.
According to this shielding effect theory, the wider the electron shells are in space, the weaker the electric attraction between electrons and the atomic nucleus.
When considering the strength per electron shell, the wider the electron shells in space, the weaker the electric interaction between the electrons and the nucleus due to the screening. We can order the electron shells s, p, d and f according to this effect as S(s) > S(p) > S(d) > S(f).
What is the Difference Between Effective Nuclear Charge and Shielding Effect?
Effective nuclear charge can be described as the actual amount of positive charge experienced by an electron in a multi-electron atom. Shielding effect is the reduction of the attraction force between electrons and the atomic nucleus in an atom, which reduces the effective nuclear charge. The key difference between effective nuclear charge and shielding effect is that effective nuclear charge is the attractive positive charge of nuclear protons acting on valence electrons, whereas shielding effect is a reduction in the effective nuclear charge on the electron cloud that forms due to a difference in the attraction forces on the electrons in the atom.
The below infographic presents the differences between effective nuclear charge and shielding effect in tabular form for side-by-side comparison.
Summary – Effective Nuclear Charge vs Shielding Effect
Effective nuclear charge and shielding effect are important terms in chemistry regarding the properties of an atom. The key difference between effective nuclear charge and shielding effect is that Effective nuclear charge can be described as the actual amount of positive charge experienced by an electron in a multi-electron atom while shielding effect is the reduction of the attraction force between electrons and atomic nucleus in an atom, which reduces the effective nuclear charge.
Reference:
1. “6.18: Electron Shielding.” Chemistry LibreTexts, Libretexts, 30 Apr. 2022.
Image Courtesy:
1. “Effective Nuclear Charge” By Own work – Effective Nuclear Charge.gif (CC0) via Commons Wikimedia