electronegativity scales and its advantages and numericals

electronegativity scales and its advantages and numericals

4.Sanderson's scale of electronegativity:
this scale is based upon new quantity called
stability ratio=E.D/E.Di

stability ratio of an atom is defined as ratio of average electron density (E.D) around the nucleus and it's ideal hypothetical electron density (E.Di) which the atom would have if it work on inert atom.

stability ratio=E.D/E.Di

A/c to sanderson's stability ratio of an atom measure it's electronegativity
X(A) (sanderson) = E.D/E.Di

Electronegativity on pauling scale:

X(pauling) = 0.21(X(A)sanderson ratio) +0.77

5.Mulliken zaffee electronegativity scale:

Zaffee and his coworker extended the Mulliken definition and suggested that electronegativity of an atom is different in different environment some of these factor which affect electronegativity are

1.Oxidation state:
more is the oxidation state ,more is the attraction for electron, hence more will be the electronegativity. so pb^+4 is more electronegativity than pb^+2.

2 .Hyberdistaion:
Hyberdistation also affect electronegativity.
sp^3 25℅ s character
sp^2 33.3℅ s character
sp 50℅ s character

s orbital are more penetrating (s>p>d>f) so hybrid orbital with greater s character will be more electronegativity. so sp carbon atom is more electronegativity than sp^2 and sp^3 hybridisation of carbon atom.

4.Positive charge:
an atom with positive charge will attract electron more readily than a neutral atom .so positive charge atom are more electronegativity than neutral atom.

5.Bond order:
more is the bond order, more will be the electronegativity.

eg. carbon of alkyne is more electronegativity than carbon atom of alkene.

numerical
Question1
The internuclear distance in Kcl is 3.14A°.calculate ionic radii of K+ and cl- using Pauling method?
ans
zeff nuclear charge of K^+

K^+ 1s^2 2s^2 2p^6 3s^2 3p^6
S= 7×0.35+8×0.85+2×1.00
S=11.25
zeff=Z-S=19-11.25=7.75

zeff nuclear charge of Cl^-

Cl^- 1s^2 2s^2 2p^6 3s^2 3p^6
S= 7×0.35+8×0.85+2×1.00
S=11.25
zeff=Z-S=17-11.25=5.75

now radius directly proportional to 1/zeff

r=C/zeff
r(k^+) = C/7.75
r(cl^-) =C/5.75

r(k^+) +r(cl^-) = 3.14A°
putting value
C/7.75+C/5.75=3.14A°
C =10.36

r(k^+) = C/7.75=10.36/7.75=1.34A°
r(cl^-) =C/5.75=10.36/5.75=1.80A°

Comments

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