PolarityCh 6.2b

Diatomic compounds share electrons equally. Equal forces pulling on

the shared electrons

What happens when atoms do NOT share electrons equally? Unequal forces pulling on

the shared electrons

Diatomics

Unequal Sharing of ElectronsElectronegativity = Atom’s attraction for

electrons Larger value stronger attraction

Electronegativity trends (attraction for electrons): Right side of periodic table: high

Exception for noble gases (Group #8A) - none Left side of periodic table: low Top of a group: higher Bottom of a group: lower

Polar Covalent Bond:Determine by electronegativity

Higher electronegativity partial negative chargeLower electronegativity partial positive charge.

Unequal Sharing of Electrons

Prof Mokeur’s Periodic Table

Shared electrons in a hydrogen chloride molecule spend less time near the hydrogen atom than near the chlorine atom.

Unequal Sharing of Electrons

How to predict what type of bond will form between two

atoms:Non-polar covalent

Electronegativity difference is <0.5Polar covalent

Electronegativity difference is >0.5 and <2.0 (Between 0.5-1.9)

Ionic bondElectronegativity difference is >2.0

ExamplesBoron and Hydrogen

Electronegativities: B = 2.0 H = 2.1Difference:

Potassium and Iodine: Electronegativities: K = 0.8 I = 2.7Difference:

Sodium and ChlorineElectronegativities: Na = 0.9 Cl = 3.0Difference:

ExamplesBoron and Hydrogen

Electronegativities: B = 2.0 H = 2.1Difference: 0.1 non-polar covalent

Potassium and Iodine: Electronegativities: K = 0.8 I = 2.7Difference:

Sodium and ChlorineElectronegativities: Na = 0.9 Cl = 3.0Difference:

ExamplesBoron and Hydrogen

Electronegativities: B = 2.0 H = 2.1Difference: 0.1 non-polar covalent

Potassium and Iodine: Electronegativities: K = 0.8 I = 2.7Difference: 1.9 polar covalent

Sodium and ChlorineElectronegativities: Na = 0.9 Cl = 3.0Difference:

ExamplesBoron and Hydrogen

Electronegativities: B = 2.0 H = 2.1Difference: 0.1 non-polar covalent

Potassium and Iodine: Electronegativities: K = 0.8 I = 2.7Difference: 1.9 polar covalent

Sodium and ChlorineElectronegativities: Na = 0.9 Cl = 3.0Difference: 2.1 ionic