1. Electronegativity and Bonding

2. Electronegativity and Bonding
Electronegativity (EN) is a measure of an atom’s ability to attract electrons away from other atoms.
Atoms with high electronegativity values (EN’s) are the best electron attractors and atoms with low electronegativity values (EN’s) are the worst electron attractors.
The electronegativity scale is a relative (arbitrary) scale based on the element fluorine, because fluorine is the best of the best electron attractors

3. Electronegativity and Bonding
NOTICE: Most noble gases do not have EN values assigned because they do not attract electrons. The reason will be explained later.

4. Electronegativity and Bonding
Ex. (1) As atomic number increases in group-1, the EN _________________________.
Ex. (2) As atomic number increases in period-3, the EN _________________________.
Ex. (3) Which of the following atoms would be the worst electron attractors?
(1) Li (2) Ba (3) S (4) Sn
decreases
increases

5. Electronegativity and Bonding
Electronegativity difference (ΔEN) can be used to predict the type of bonding present in a compound.
Using the Periodic Table to predict bonding type is a more reliable method.
∆EN
Nonpolar
Covalent
Bonding
Polar
Covalent
Bonding
Ionic
Bonding
1.7

6. Electronegativity and Bonding
Electronegativity difference (ΔEN) indicates the degree of polarity in a chemical bond.
The larger the electronegativity difference (ΔEN) is between two bonded elements, the greater the bond polarity will be.
H2O has a more polar bond than CO2.
ΔEN H2O = ΔEN CO2 = 0.9

7. Electronegativity and Bonding
Ex.(1) If element M has an electronegativity of 0.9 and element X has an electronegativity of 2.6, then the type of bonding present in the compound M2X is most likely be ________________________.
Nonpolar
Covalent
Bonding
1.7
∆EN
Polar
Ionic
EN of X = 2.6
ionic -
EN of M = 0.9
ΔEN = 1.7

8. Electronegativity and Bonding
Ex.(2) If element Z has an electronegativity of 2.6 and element X has an electronegativity of 3.2, then the type of bonding present in the compound ZX4 is most likely be ________________________.
Nonpolar
Covalent
Bonding
1.7
∆EN
Polar
Ionic
EN of X = 3.2
polar covalent -
EN of X = 2.6
ΔEN = 0.6

9. Electronegativity and Bonding
Ex.(3) Which of the following compounds has the greatest degree of bond polarity present?
(1) HCl (3) Br2
(2) SO (4) NH3
Nonpolar
Covalent
Bonding
1.7
∆EN
Polar
Ionic