Chemical Bonding and Nomenclature
Jan 31, 2013
BW: which of the following is an ion?
Which is a compound?
NaCl
Mg2+
HNO3
HNO3+
Reflection will be: answer to the objective.
Chemical Bonding and Nomenclature
Jan 31, 2013
I’ll collect BW on Monday not today,
not tomorrow. Tomorrow is computer
lab day.
Reflection will be: answer to the objective.
Chemical Bonding and Nomenclature
Obj: know the difference between an ion,
a polyatomic ion, a compound, a
chemical name, and a chemical formula.
ACE THIS TEST
Chemical Bonding and Nomenclature
Ionic Compounds W/ a Transition Metal.
Fe (III) Fe3+
Mg (IV) Mg 4+
Cu (II) Cu 2+
Chemical Bonding and Nomenclature
The oxidation state of an element is related
to the number of electrons that an atom loses,
gains, or appears to use when joining with
another atom in compounds. It also determines
the ability of an atom to oxidize (to lose
electrons) or to reduce (to gain electrons).
Almost all of the transition metals have multiple
potential oxidation states. i.e Fe, Cu, Au, Ag etc
Some elements (transition metals)
use roman numerals to specify their charge.
Roman numeral
Charge
I
+1
II
+2
III
+3
IV
+4
V
+5
VI
+6
Chemical Bonding and Nomenclature
Review Transition metals:
Multiple-Charge Transition Metals
Question
Fe(2+)
Fe(3+)
Cu(1+)
Cu(2+)
Au(1+)
Au(3+)
Hg(1+)
Hg(2+)
Answer
Iron(II)
Iron(III)
Copper(I)
Copper(II)
Gold(I)
Gold(III)
Mercury(I)
Mercury(II)
Mercury(II)common
name
Mercury(I)common
name
Iron(II)
Iron(III)
Copper(I)
Copper(II)
Gold(I)
Gold(III)
Mercuric
Mercurous
Ferrous
Ferric
Cuprous
Cupric
Aurous
Auric
Chemical Bonding and Nomenclature
Common Names:
Na2CO3 = sodium carbonate. ( This is a useful chemical in
purifying others; it is sometimes called washing soda)
KNO3 = potassium nitrate ( This is an ingredient of
gunpowder and it is also found in fertilizer.)
Chemical Bonding and Nomenclature
Mercury(II)common
name
Mercury(I)common name
Iron(II)
Iron(III)
Copper(I)
Copper(II)
Gold(I)
Gold(III)
Mercuric
Mercurous
Ferrous
Ferric
Cuprous
Cupric
Aurous
Auric
Chemical Bonding and Nomenclature
the same rules apply, but you have to learn the names and charges of comm
Polyatomic Ion
Name
OH-1
hydroxide
SO4-2
sulfate
PO4-3
phosphate
NO3-1
nitrate
CO3-2
carbonate
HCO3-1
hydrogen carbonate or bicarbonate
ClO3-1
chlorate
NH4+1
ammonium
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OBJ: Know the difference between the two,
by drawing each.
refer to Text: pages 212- 214)
8
Monday Feb 4
BW: What is the difference between a
molecule and a compound?
Reflection. Diagraming chemical molecules
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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
C2H6
8-2 Bonding
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H2 is a diatomic molecule because;
is has TWO atoms in its formula
it is covalently bonded
All molecules are covalently bonded. All
must share electrons.
Video.
http://www.brightstorm.com/science/chemist
ry/chemical-bonds/covalent-bonds/
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In drawing out; they appear
1. H—H
Draw the bonding arrangement for Fluorine,
a diatomic molecule;
Start with the LDD lewis dot structure:
then add the shared bonds.
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2. F ---F
3. H20
4. NH3 ammonia
5. Methane: CH4
6. BCl3 boron Trichloride
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7. HCl = Hydrogen chloride
YOU DO THESE
8. H202 DihydrogenDioxide
YOU DO THESE
8. H202 DihydrogenDioxide
9. PCl3
Phosphorus
Trichloride
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video
http://www.youtube.com/watch?v=6_YhSLn
AmVo
electronegativity page….
electronegativity page 238
Can you predict bonding type?
(discuss in your table)
Can you predict Covalent? Ionic? Polar
covalent?
polar)
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you
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polar
http://www.youtube.com/watch?v=IBtCV12i2
BQ
Double and Triple Bonds…..
atoms form double or triple bond if they can
form noble gas configuration.
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12. 02 Diatomic molecule - - - - > is a double
bond.
13. N is a triple bond , also a diatomic
molecule
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.
Electron-deficient compounds are
compounds in which an element has an
incomplete octet. Some elements, notably
H, Be, and B, often have fewer than eight
electrons
Lewis
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tostructures.
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Hydrogen has a single valence electron in a
1s orbital and therefore accommodates only
two electrons when it forms covalent bonds.
Therefore, it almost always forms only one
chemical bond to another atom and does
not accommodate lone pairs of electrons.
Beryllium
electrons)
boron
I want(two
youvalence
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a friendand
of mine?
(three valence electrons) often
accommodate only four or six electrons,
respectively, in Lewis structures.
For example, BF3 is an electron-deficient
compound.
Each fluorine has a complete octet (six
nonbonding electrons plus two bonding
electrons), but boron has only six electrons
(six Ibonding
electrons
andano
lone of
pairs).
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Changing a fluorine lone pair to a bonding
pair would alleviate the electron deficiency,
but fluorine's high electron affinity means
this element is unlikely to share its
nonbonding electrons with boron.
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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tonew
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compounds.
In the
compound,
both
N
and B have full octets and the neither
compound is electron deficient.
Free radicals are compounds with at least
one unpaired electron. Free radicals can
also be electron-deficient compounds.
Nitrogen monoxide (nitric oxide, NO) is a
free-radical compound because it is an oddI want
you towith
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a friendelectrons
of mine?
electron
molecule
11 valence
and 1 unpaired electron.
Notice that the unpaired electron is placed
on the nitrogen atom.
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.
Elements with an expanded valence (also
called an expanded octet) have more than 8
electrons (often 10 or 12) in a Lewis
structure.
Elements in the third period and below, such
I want yousulfur,
to meet
friend of
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as phosphorus,
andabromine,
often
have an expanded valence because of their
larger radii (when compared to the secondrow elements) and the availability of empty
d orbitals in the valence shell.
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
Example Problem: Draw Lewis
Structures (Octet Rule Exceptions)
Draw the Lewis structure for
ClO
IBr3 I want you to meet a friend of mine?
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)
This is an odd-electron molecule (a free
radical). The unpaired electron is placed on
chlorine because oxygen has a high
electron affinity.
Step 1: 7 + (3 × 7) = 28 valence electrons
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(or 14
pairs) you to meet a friend of mine?
Steps 2 and 3:
Iodine has a lower affinity for electrons that
bromine, so it is the central atom.
Steps 4 and 5:
Iodine is in the fifth period and therefore can
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:
I want
youfifth
to period
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a friend
of mine?
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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