Chemical Bonding and Nomenclature
Feb 5, 2013
BW : How is the octet rule related to
covalent bonding? Pg 217.
Obj: Use the octet rule to diagram
molecules
Reflection: Diagram CH4 showing LLD
and (covalent) bonding.
Chemical Bonding (covalent)
After reading page 217, Discuss at your table,
(1) how the octet rule is similar when
comparing ionic bonds, and covalent bonds.
(2) What is different when using the octet rule
in ionic bonds vs covalent bonds?
Take 7 minutes to discuss at your table. Be
able to answer the question (talk out).
Be able to draw a diagram that illustrates the
answer. (participation pts hand-out)
Chemical Bonding and Nomenclature
The
ELECTRONEGATIVITY
of an element is: the tendency of an atom to
attract electrons.
Chemical Bonding and Nomenclature
Review Transition metals:
Chemical Bonding and Nomenclature
Review Transition metals:
Electronegativity: the degree to which an
element can bond.
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Draw a molecule, using circles for atoms
Draw a compound, using circle for atoms
draw a diatomic molecule
Draw the molecular formula for C2H6
.When to use numbers before a compound.
2NaCl = 2
of NaCl…?
NaCl2 = 2 atoms of Cl
Now, molecule is frequently used, however,
the accurate way to word the above is, 2
ions of NaCl have formed an ionic
compound.
Video.
In drawing out; they appear
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1. H—H
Draw the bonding arrangement for Fluorine,
a diatomic molecule;
5. Methane: CH4
6. BCl3 boron Trichloride
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7. HCl = Hydrogen chloride
YOU DO THESE
8. H202 DihydrogenDioxide
electronegativity page 238
Can you predict bonding type?
(discuss in your table)
Can you predict Covalent? Ionic? Polar
covalent?
polar)
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polar
http://www.youtube.com/watch?v=IBtCV12i2
BQ
14. C02 Carbon Dioxide is a double bond.
15. NF3
16. SB2
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8.2c Exceptions to the Octet Rule
Although many Lewis structures follow the
octet rule, there are exceptions.
Therefore, it almost always forms only one
chemical bond to another atom and does
not accommodate lone pairs of electrons.
Beryllium
electrons)
boron
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(three valence electrons) often
accommodate only four or six electrons,
respectively, in Lewis structures.
The electron deficiency means that BF3 is a
highly reactive compound. For example, it
reacts readily with NH3.
In this reaction, the lone pair on N forms a
new covalent bond between the
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compounds.
In the
compound,
both
N
and B have full octets and the neither
compound is electron deficient.
In general, the odd electron in free radicals
is not located on oxygen because of its high
electron affinity.
Free radicals are highly reactive species
because the unpaired electrons react with
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otherI molecules.
Pure NO, for example, reacts readily with
halogens, O2, and other free radicals.
Consider the Lewis structure of SF4.
Each fluorine has a satisfied octet (6
nonbonding electrons plus 2 bonding
electrons), but the central sulfur atom has
an expanded octet with 10 electrons around
it (8 bonding electrons and 2 nonbonding
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electrons).
Example Problem: Draw Lewis
Structures (Octet Rule Exceptions)
Draw the Lewis structure for
You are asked to draw the Lewis structure
for a molecule or ion with a central atom that
can have an expanded valence.
You are given the chemical formula for a
molecule or ion.
Step 1: 7 + 6 = 13 valence electrons (or 6
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pairsI and
1 unpaired
electron)
Step 1: 7 + (3 × 7) = 28 valence electrons
(or 14 pairs)
Steps 2 and 3:
Iodine has a lower affinity for electrons that
bromine, so it is the central atom.
Steps 4 and 5:
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Iodine
is in the
therefore
can
have an expanded valence.
exceptions to octet rule
http://sowl.cengage.com/ebooks/vining_owlbook_p
rototype/ebook/videos/VS_8_2_3.htm
Can you predict bonding?
BW> What is van del wahls forces (pg 240)
read and answer.
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