IGNOU MCH 18 2026 2027 - Briefly explain the concept of “Effective Nuclear Charge”

Question

Briefly explain the concept of “Effective Nuclear Charge” (?eff) in multielectron atoms.

19 Aug 2026

Answer :

Word Count : 226

Effective nuclear charge, (Z_{\mathrm{eff}}), is the net positive charge experienced by an electron in a multielectron atom. Although the nucleus has a charge of (+Ze), an electron does not experience the full nuclear attraction because other electrons partially shield it. Thus, (Z_{\mathrm{eff}}) is expressed approximately as [ Z_{\mathrm{eff}}=Z-S ] where (Z) is the atomic number and (S) is the shielding constant. In quantum chemistry, the actual electronic motion in a multielectron atom is described by a many-electron Schrödinger equation. Because electron–electron repulsion makes the equation non-separable,

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