Pauling electronegativity

Pauling electronegativity

1. Pauling electronegativity
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan Manju Desai College
Canacona Goa

2. LinusPaulingdescribedelectronegativity
as“thepowerofanatominamoleculeto
attractelectronstoitself.” Linus Pauling
Definition of Electronegativity
e
-
e
-
Atom A
Atom B

3. Calculating Electronegativity
A B
Thefactor0.208arisesfromtheconversion
electronegativityvaluesfromKcalstoelectronvolt.

4. Calculating Electronegativity
A B
E
A-B> E
A-A or E
B-B
E
A-B(measured)> E
A-B(theoretical)
Difference in the Bond Energies (Δ)
Δ = E
A-B(measured)–E
A-B(theoretical)
E
A-B(theoretical) = energy for 100% covalent bond
E
A-B(theoretical) = (E
A-A X E
B-B)
1/2
Thus
Δ= E
A-B(measured)–(E
A-A X E
B-B)
½
δ+ δ-
IfX
(A)andX
(B)are
electronegativityofindividual
atomsAandB,respectively,
than
X
(A)-X
(B)= 0.1017(E
A-A X E
B-B)
½
in kcal mol
-1
X
(A)-X
(B)= 0.208 (E
A-A X E
B-B)
½
in kJ mol
-1

5. Periodic trend in Electronegativity

6. Summary
•Fismostelectronegativeelement
•Iftwoelementhavesimilar(<1.7)electronegativity
valuesthebondiscovalentormetallic.
•Iftwoelementhavelarge(>1.7)differenceintheir
electronegativityvaluesthebondisionic
predominantly.
As Atomic number increases
•Electronegativity decreases down the group
•Electronegativity increases along the row