Fact Sheet ∣ General Chemistry ∣ Chapter 7.2 ∣ Electron Shielding and Effective Nuclear Charge

 

The effective nuclear charge is always less than the actual nuclear chargedue to ______________ effect.

the screening effect or shielding effect

We can define the amount of screening of the nuclear charge quantitatively by using a ____________-

screening constant, S. Zeff = Z - S

. A more accurate approach was developed by John Slater (1900–1976),of Variations in effective nuclear charge for valence electrons( Slater’s rules). Hwever, and we can use his approach if we limit ourselves to elements that do not have electrons in __________ subshells.

d or f

Electrons for which the principal quantum number n is larger than the value of n for the electron of interest contribute_______ to the value of S.

0

Electrons with the same value of n as the electron of interest contribute_________ to the value of S.

0.35

The value of S for Electrons that have principal quantum number n - 1 contribute _______, while those with even smaller values of n contribute _________.

0.85 and 1.00 respectively

fluorine, which has the ground-state electron configuration 1s²2s²2p⁵. For a valence electron in fluorine, Slater’s rules tell us that S =

= 10.35 * 6 + 10.85 * 2 = 3.8. (Slater’s rules ignore the contribution of an electron to itself in screening; therefore, we consider only six n = 2 electrons, not all seven). Thus, Z(eff) = Z - S = 9 - 3.8 = 5.2+

Some more basics from NCERT 11th and 12th

 

The shielding effect depends upon the ____________ of the orbitals.

electron density

One d electron does not shield another electron from the influence of nuclear charge because d-orbitals differ in _________.

direction

_______________ is approximately proportional to the total number of possible pairs of parallel spins in the degenerate orbitals.

Exchange energy

Electrons present in spherical shaped, s orbital shields the outer electrons from the nucleus ____________ as compared to electrons present in p orbital.

more effectively

Lower the value of (n + l) for an orbital, the __________ is its energy.

lower

If two orbitals have the same value of (n + l), the orbital with _____________ will have the lower energy.

lower value of n

Energies of the orbitals in the same subshell ____________ with increase in the atomic number (Z eff).

decrease

shielding of one 4 f electron by another is_________ than one d electron by another with the increase in nuclear charge along the series.

less

The almost identical radii of Zr (160 pm) and ________, a consequence of the lanthanoid contraction, account for their occurrence together in nature and for the difficulty faced in their separation.

Hf (159 pm)

The extra stability of half-filled and completely filled subshell is due to 3 reasons:____________________________,______________________________and______________________

(i) relatively small shielding, (ii) smaller coulombic repulsion energy, and (iii) larger exchange energy

Across a period, increasing nuclear charge ___________ the shielding. Consequently, the outermost electrons are held more and more tightly and the ionization enthalpy increases across a period.

outweighs

Effect of a d orbital electron is not that effective, hence the net electrostatic attraction between the nuclear charge and the outermost electron ___________ and the ionic radius ___________.

increases,decreases respectively

Labels