Approximate Electronegativity

H

2.1

            
Li

1.0

 Be

1.5

 B

2.0

 C

2.5

 N

3.0

 O

3.5

 F

4.0
Na

0.9

 Mg

1.2

 Al

1.5

 Si

1.8

 P

2.1

 S

2.5

 Cl

3.0
K

0.8

 Ca

1.0

 Ga

1.6

 Ge

1.8

 As

2.0

 Se

2.4

 Br

2.8

 

Electronegativity Difference Type of Bond Example
0.0 - 0.4 Covalent (nonpolar) H - H (0.0)
0.4 - 1.0 Covalent (moderately polar) H - Cl (0.9)
1.0 - 2.0 Covalent (very polar) H - F (1.9)
>2.0   Ionic Na+Cl-(2.1)