AP/Honors Chemistry
Review 3
1.


Octet rule
Octet rule: Atoms tend to gain, lose or share electrons
in order to have 8 valence electrons after bonding
Exceptions: When the total valence electrons is an odd
number and for H(2), Be(4), B(6)
Metal atoms: Lose their valence electrons in order to
uncover a full octet
Nonmetal atoms: Gain or share electrons to have a
total of 8 valence electrons (except H(2), Be(4), B(6))
Ionic bond
Two ways to form ionic bonds:
(1) Chemical reaction between metal and nonmetal
(2) Evaporate water that contains cations and anions
Two lattice energy factors:
(1) Proportional to ions' charge
(2) Inversely proportional to ions' radius
Electronegativity
Definition: Measures atoms ability to attract pair of
bonding electrons
Period trend: Increases from left to right

Group trend: Decreases from top to bottom



2.


3.

4.

Polar bond
Polar bond: Result of uneven sharing of bonding
electrons

 notation: Atom with higher electronegativity (-) and
atom with lower electronegativity (+)

+ notation: Atom with lower electronegativity gets +
sign and atom with higher electronegativity gets 
5. Bond distance and strength

Two factors: Polar bonds and multiple bonds have
shorter bond distances than single, non-polar bonds

Bond distance and bond strength: Short bonds are
stronger
6. Lewis structures
Lewis
Lewis
Molecule
Skeleton
Valence eeStructure
•• •• ••
•• •• ••
6 + 2(7)
: F–S–F :
: F–S–F :
20
SF2
= 20
•• •• ••
•• •• ••
•• •• ••
•• •• ••
8 + 2(7)
: O=S–O :
: O–S–O :
20
SO2
= 22
•• •• ••
••
•• •• ••
•• •• •• ••
6
+
2(6)
: F–Xe–F :
: F–Xe–F :
20
XeF2
= 18
•• •• ••
•• •• ••
7. Resonance

Resonance: More than one place for a double bond

Delocalization: bond shared among all bond positions

Bond order: Average number of bonds per bonding pair
8.

Formal charge
Equation: Formal charge = valence e- – [2(:) + (–)]

Best Lewis structure: Zero formal charges, with negative
value going to atom with highest electronegativity
Hybrid orbitals
Description: s and p atomic orbitals combine to form
from 2 to 6 electron domains around central atom
Sigma vs. pi bonds: First bond between atoms is sigma,
, second and third bonds are pi, 
Non-hybridized valence electrons: pi bond electrons
9.



Name ________________________
Period _____
10. Electron domain and molecular geometry
Geometry Around Central Atom
# Hybrid

Electron # pairs of dots around central atom
Domain 0
1
2
3
sp
180o
linear
linear
2
3
sp2
120o
trigonal
planar
bent
linear
4
sp3
109.5o
tetrahedral
trigonal
pyramidal
bent
linear
sp3d
90o
120o
trigonal
bipyramidal
seesaw
T-shaped
linear
5
6
sp3d2
90o
octahedral
square
square
pyramidal planar
decreasing ideal bond angle 
11. Polar molecules

Polar conditions:
(1) : around central atom except sp3d-linear & sp3d2square planar,
(2) different perimeter atoms

Polar properties:
(1) soluble in water
(2) high boiling and melting points
(3) decrease evaporation
12. hydrocarbons

Description: molecule with H and C

General properties: Nonpolar, fuels
13. Alkanes, alkenes and alkynes
Hydrocarbon
Bonding
# of hydrogens
C–C
2xC + 2
alkane
C=C
2xC
alkene
2xC – 2
alkyne
CC
14, Prefix and suffix notation for hydrocarbon names
1
2
3
4
5
6
7
8
9
10
meth eth prop but pent hex hept oct non dec
single bond
double bond
triple bond
ane
ene
yne
15. Examples of hydrocarbon names and Lewis structures
2-pentyne
1,3-butadiene
2-methylpropane
C–CC–C–C
C
|
C–C–C–C
C=C–C=C
2-2dimethylpropane
3,3-diethylhexane
C2H5
C
|
|
C–C–C–C–C–C
C–C–C
CC
|
|
C2H5
C
16. Functional groups
Functional Group
Altered Property
Altered Name
Name
Group
C-OH
soluble
...anol
alcohol
C(=O)-OH
release H+
..anoic acid
acid
absorb H+
..yl amine
amine (CH3)n-N:
17. Structural isomers (C2H2F2)
1,2-difluoroethene
1,1-difluoroethene
F F
F
|
|
|
CH=CH
F–C=CH2
18. Geometric isomers (C2H2F2)
cis
trans
F
F
F
H
\
/
\
/
C=C
C=C
/
\
/
\
H
H
H
F
ethyne