Organic Chemistry
Nothing to do with organs
Bonding in organic chemistry
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Covalent bonds – sharing electrons
Nonpolar covalent bonds –
electronegativity difference of less than
0.5 units
Polar covalent – EN difference of 0.51.9 units
EN difference of >1.9 is ionic (“DEN”)
C–C DEN = 0, NPC
Bonding in organic chemistry
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C–H DEN = 0.35, NPC
H–Cl DEN = 0.94, PC
d+
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H
Cl d–
Lewis structures show all valence
electrons – nonbonding as pairs of
dots, and bonding as lines
Bonding in organic chemistry
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methanol
All atoms must have full octet
H, halogens make one bond
Bonding in organic chemistry
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(halogens have three lone pairs)
O and S make two bonds (w/two lone
pairs)
N makes three bonds (one lone pair)
C makes four bonds
Double bonds – 4e-, represented by
two lines
Bonding in organic chemistry
formic acid
 Triple bonds
acrylonitrile
Bonding in organic chemistry
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acetylene
Shapes of molecules
Bond angles – determined by valenceshell electron pair repulsion (VSEPR)
between ligands (bonded group or
lone pair)
Molecule Shapes
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Four groups – tetrahedral shape,
109.5º bond angles – ex. CH4 methane
Molecule Shapes
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If one of the four groups is a lone pair,
then the shape is trigonal pyramidal
(ammonia)
Molecule Shapes
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H-N-H angles are 107.3º
In water (bent geometry) H-O-H angles
are 104.5º
Molecule Shapes
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Three groups – trigonal planar shape,
120º bond angles – BF3
Molecule Shapes
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If ligands are not identical, then angles
will deviate from 120º
Molecule Shapes
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Two groups – linear shape, 180º bond
angles
Molecule Shapes
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Molecular polarity – a molecule is polar
if it has polar bonds and asymmetry
Polar examples: water, ammonia,
methanol
Nonpolar examples (with polar bonds):
CO2, CCl4
Nonpolar examples (no polar bonds):
methane, benzene
Functional groups
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Contain N, O, S, or halogens
Are often the site of chemical reactivity
of a molecule
Used to divide organic compounds into
classes
Used as basis for naming organic
compounds
Functional groups
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Alcohols -OH (hydroxyl)
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primary (1º) alcohol (methanol)
Functional groups
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secondary (2º) alcohol
(2-propanol or isopropanol)
CH3CHOHCH3
Functional groups
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Tertiary (3º) alcohol (2-methyl-2propanol or t-butyl alcohol)
Draw all the alcohol
isomers of C4H10O
and label each as a
primary, secondary or
tertiary alcohol.
Functional groups
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Amines –NR2 (amino – R can be H or
a carbon containing group)
Ammonia – NH3
1º amine – CH3CH2NH2
2º amine – CH3NHCH3
3º amine – (CH3)3N
Functional groups
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Aldehydes and ketones R2C=O
(carbonyl)
Ketone (acetone)
Aldehyde (acetaldehyde)
Functional groups
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Carboxylic acids RCOOH (carboxyl
group)
Acetic acid