Chapter 6: Part 2
-
Diatomic Molecules
o
7 nonmetals are so ______________ that they will NEVER be found alone.
o
Often these elements are bonded to themselves forming what chemists call
diatomic molecules.
o
The 7 diatomic molecules are:

-
_____, _____, _____, _____, _____, _____, _____
Polarity of Covalent Bonds
o
Covalent bonds can be polar or non-polar depending upon the electronegativity
of the atoms involved.

Non-polar covalent bond:


Similar electronegativity = electrons _________ _________
Polar covalent bond:

Differing electronegativity = electrons will be more __________
to the atom with ____________ electronegativity
-
VSEPR: Polarity of Molecules
o
Just as covalent bonds can be polar or non, entire molecules can be defined as
either polar or nonpolar.
o
VSEPR (___________ _________ ___________ _______
____________) – atoms will orient themselves as far away from each other
as possible, while still being bonded together
o
There are 6 main shapes associated with simple molecules. To determine the
shape of a molecule, follow these rules:

Count the number of __________. Refer to the “shape chart” below to
see which shapes are possible for this number of atoms.
Number of Atoms
Unshared Pairs of
Middle Atom
3
3
4
There is no central
atom
No
Yes
No
4
Yes
5
No
2
Shape
Polar or Non-polar
Linear
Can be either
Linear
Bent
Trigonal Planar
Tetrahedral with
Pyramidal Base
Tetrahedral
Non-polar
Polar
Non-polar
Polar
Non-polar


Draw the Lewis structure. Look at the atom in the middle of the molecule.
 No Unshared Pairs = all 8 electrons of the middle atom are
involved in bonds
 Unshared Pairs = some of the 8 electrons of the middle atom
are NOT involved in bonds
Refer to the chart, and determine the shape and polarity of the molecule.
Sketch the Lewis Structures and Molecular Geometry for the following molecules and
determine whether they are polar or non-polar.
Molecule
Lewis Structure
Molecular Geometry
Polar or Non-polar
SiS2
NOF
CH4
HF
-
Intermolecular Forces
o
Molecules can experience ____________ forces.

The positive portion of one molecule is attracted to the negative portion of
another molecule.
o
There are three basic attractive forces between molecules:

__________ ___________ __________

The ___________ intermolecular force.
o
They arise from the _________ motion of electrons,
which causes the side of a molecule to become
momentarily positive or negative.

The only force that all molecules experience regardless of whether
they are polar or not.

___________- ___________ __________

Occur in _________ molecules.

The positive end of one molecule forms an attractive bond with the
negative end of another molecule.

______________ ______________

The ____________ intermolecular force.

Involves a hydrogen atom in a polar molecule bonding with atoms
like O, N, or F.
o
The positive hydrogen is attracted to the unshared electron
pair of the O, N, or F atom of another molecule.
-
Ionic Bonds
o
Ionic bonds involve ___________ and ___________________
o
Ionic bonds are not _____________.
o
They form _____________ _________, which are the lowest possible
number of positive and negative charges that will result in a net charge of zero.

Example: Calcium ion = Ca2+, Fluorine ion = F-. The formula unit for
calcium fluoride would be _________.
o
Formula units, unlike molecules, always experience strong forces.

o
Ionic compounds will combine in geometric patterns called ____________.

o
These forces are the reason that most ionic compounds are ________.
Crystals form because grouped formula units have lower __________.
In solution, ionic compounds are _________________.

Electrolytes conduct an electric current through the solution.
-
Metallic Bonds
o
Metallic bonding involves _____________.
o
Metal atoms aren’t as __________ as non-metal atoms.

o
The electrons in metals move more freely.
The electrons within a group of metal will move around and are not attached to
any one atom.

o
These electrons are said to be ________________.
Metallic bonding is the attraction of atoms to the surrounding delocalized
“electron sea.”
o
These delocalized electrons are responsible for the many properties of metals:

_________ ______________ – electrons can easily move

__________– no poles to prevent atoms from moving past one another

________– vacant p and d orbitals

Excited electrons enter these orbitals and as they leave, they will
release a silver or gold colored light.