BELLWORK- Determine ShapeDraw the Lewis Dot Structure and the 3D structure for ethane (C2H6) and ethene (C2H4). Do these molecules have any polar bonds?

In reviewEqual sharing of electrons = covalent

LOW electronegativity difference

Unequal sharing of electrons = polar

MEDIUM electronegativity difference

Transfer of electrons = ionic

HIGH electronegativity difference

2 bonding domains

Three bonding domains

Four bonding domains

Three bonding and one lone pair

Two bonding and two lone

pairs

Bond polarity and molecule shape determine if a molecule is polar

Bond polarity --- When a bond has a partial negative charge on one atom and a partial positive charge on the other atom.

Molecule shape--- the arrangement of atoms in three dimensions (3-D)

A polar molecule has polar bonds and asymmetry

A polar molecule has polar bonds and asymmetry

Polar bonds Non-polar molecule

Symmetry- all sides are the same

δ-

δ-

δ-

δ-δ+

A polar molecule has polar bonds and asymmetry

Polar bonds Non-polar molecule

Symmetry- all sides are the same

Polar bonds Polar molecule

Asymmetry- has different sides

δ-

δ-

δ-

δ-

δ-

δ+δ+

negative side

Positive side

If the electrons are not distributed equally, the

molecule is polar.

The molecule has a negative

end and a positive end.

A polar molecule has a partially positive side and a partially negative side.

The arrow labels the molecular polarity.

It shows that electrons are mostly by the oxygen atom

OH H

Polar molecules are affected by electric fields

Polar molecules have two poles; one is partially positive and one is

slightly negative.

Positive end

Negative end

N

HHH

The positive pole (+) is attracted to

negative ions

and

the negative poles(-) in other polar molecules.

POLAR MOLECULES INTERACT!!

+

POLAR MOLECULES INTERACT!!

The negative pole (-) is attracted to

positive ions

and

the positive poles(+) in other polar molecules.

Water is a molecule that has two polar O-H bonds.

The electrons are not distributed evenly, so the water molecule is polar.

The negative pole is at the oxygen.

O is more electronegative than H, so electrons are

pulled toward O.

Also, there are two lone pairs around oxygen.

negative end

positive end

Na+(aq)

A dissolved sodium ion

Water is very good at dissolving salts because it can surround anions & cations.

Practice- Using last night’s homework assignment, label the molecular polarity

on the four pictures

H F

For the rest of the period work on your molecular modeling lab•Find a molecule that contains polar bonds•Build the molecule using a molecular modeling kit•Draw a sketch of the molecule

•Label the bond polarity using δ+ and δ- •Label the molecular polarity using

HW- complete bonding practice problems #1-#17

Tuesday = cover network solids and intermolecular forces. HW- Section 8.4

Block Day = Complete modeling lab, plus finish

bonding practice problems. Friday = Chapter Eight QUIZ!!

Practice- Draw the 3D structures for these molecules and label the bond polarity and the molecule polarity.

1. H2O

2. CH4

3. CH3F

4. CH3CH3

5. CH3CH2OH

6. NH3

7. CO2

8. CH2CH2

9. HCN

10.

11.