Polarity

Electronegativity EN

•Describes an atom’s ability to compete for electrons with other atoms to which it is bonded.

∆ E.N. gives a clue at so how ionic a compound is:Ex: HCl ∆ E.N. 3-2.1 = 0.9 vs. H-C 2.5-2.1 = 0.4HCl bond has more “ionic character” it is said to be more polar because Electrons are not shared equally.

ΔEN =2.1-2.1=0

ΔEN =3-2.1 = 0.9

ΔEN =3.0-3.0=0

bond has a “dipole” to poles one is slightlyPositive the other is slightly negative.

ΔEN 0-.5 non polar, ΔEN 0.6-1.6 polar covalent, ΔEN 1.7< Ionic

• Δ EN for HCl

• 3.0 – 2.1 = 0.9

• Ionic character from graph 20%

What is the ionic character for an KBr bond?

Dipole

•Polar bond • Molecular dipole

• (Dipole moment)

Look for polarity in a bondLook for symmetryIn a molecule

Think about the geometry

Draw the Lewis structure for N3-

a. What is the electron geometry aroundthe central Nitrogen?

b. Does the ion have a dipole?

Predict the shape and find the dipole moment

•HCN

•SO3

•CS2

•OCS

•SOCl2•POF3