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Polar Bears and Penguins
Making Sense page 135
Making Sense -133
The ability of an atom to attract electrons
shared between two atoms is called
electronegativity.
– High electronegative atoms (polar bears) gain a
- (partial negative)
– Low electronegative atoms (penguins) gain a +
(partial positive)
Unit 2 • Investigation IV
Water Molecule:
Oxygen attracts the shared electrons
towards itself so it is partial negative.
Hydrogen is less electronegative so the
shared electrons are pulled away. It
becomes partially positive.
Direction of pull
Unit 2 • Investigation IV


– There is a crossed arrow to show the
direction of the dipole in HCl. The crossed
end of the arrow indicates the positive (+)
end of the polar bond and the arrow
points in the direction of the negative (-)
end.
N
O
N
O
Nonpolar molecules
They have symmetrical shapes like linear and tetrahedral
and identical surrounding atoms. (Bonded electrons are being pulled but
they are canceled out.
H
P
H
N
H
H
H
H
Se
H
H
Cl
H
Polar molecules
It is not symmetrical. There are different shapes.
Unit 2 • Investigation IV