Download VSEPR and Polarity

VSEPR and Polarity



Since all atoms have different electronegativities, a
“Tug of war ” for the electrons in a bond begins
when atoms bond.
When an atom bonds with another one of itself
(example F-F), the difference in electronegativity
is zero . This is known as nonpolar covalent or
pure covalent bond.
When an atom bonds with different atoms, they
nonpolar covalent bonds,
can be polar or _________
depending on the differences in electronegativities.
What happen when the
electronegativity isn’t equal
large , an
bonding

When the difference in electronegativity is
ionic
electron is transferred and
results.

When the difference in electronegativity is
very ____________,
small (<0.5) the electrons are __________
shared
______
____________
and nonpolar bonding results.
equally
When the difference in electronegativity is moderate ,
there is unequal sharing. Resulting in a polar
covalent.
 As a result, the electrons spend more time around the
more electronegative (
stronger ) atom, which
negative
makes it slightly
. The weaker atom
positive
becomes slightly
.
 This results in the polar bond being a dipole
– two
poles

Polarity of Molecules

Overall, molecules can be polar or non-polar ,
depending on the results of the molecular
of war .”
“ Tug
If the VESPR shape makes it a symmetrical
molecule then the result is nonpolar
.
asymmetrical
 If VESPR shape makes it a
molecule then the result is polar
.
 Let’s look at H2O
polar , because its shape is
 Water is
Asymmetrical (bent)

A Dissolving Situation

Ability of a substance to dissolve is based on
polarity … like
dissolves like .
polar dissolves polar and nonpolar
 So,
dissolves non-polar.
 Water is polar, so it dissolves polar substances
Forces

Ionic and covalent bonds are called
intramolecular
(within molecules)

Intermolecula – between molecules – also called
Van rder Waals
forces – WEAK
Intermolecular forces are always weaker than
intramolecular forces.

Types of van der Waal forces
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2
Dipole-dipole interactions – between ___
polar covalent molecules
_______
Dipole-induced dipole interactions – between
1 _______
polar and ___
1 _________
___
nonpolar covalent
molecules
2
London’s Dispersion Forces – between ___
nonpolar
____________
covalent molecules
H in one
Hydrogen Bonding – between ___
N ___,
O or ___,
F in another
molecule with ___,
strong
molecule. It is an unusually __________
bond.