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
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