The reducing effect of the nuclear charge by the inner electrons for on outer electron
Channel: Doubtnut
Date: 26/04/2020

The reducing effect of the nuclear charge by the inner electrons for on outer electron is termed aas shielding (or screening). As a result of shielding, the outer electrons in an atom always experience less nnuclear charge than the actual nuclear charge Z. The effective nuclear charge `(Z^(**))` as experienced by an electron is then obtained by subtracting the total shielding contributions from alll the other electrons (i.e., except the one under consideration) from the actual nuclear charge.   `Z^(**)=Z-sigma`   Where `sigma`=sum of the shielding contributions. The rules for estimating contributions to `sigma` are as follows (Slater's rule) Contribution to shielding by each electron is :   `|{:("Electron","All Higher","Same","Group","Group"le),("Grpoup","Group","Group",n-1,n-2),(1s,"  "0,0.30,-,-),((ns,sp),"  "0,0.35,0.85,1.00),((nd)or(nf),"  "0,0.35,1.00,1.00):}|`   According to Slater's treatment, the energy of an electron in nth shell of an atom having atomic number Z is given by the empirical equation   `E=-13.6((Z^(**))/(n))^(2)eV`   `Z^(**)` = effective nuclear charge    The size of isoelectronic species `-F^(-),Na^(+)` and `Mg^(2+)` is effected by: