Organic Chemistry

Branch of chemistry dealing with carbon

molecules.

Hydrocarbons

Compounds containing only carbon & hydrogen

Why can carbon form so many compounds?

It can form up to 4 covalent bonds with other carbon atoms.

What is the maximum # of bonds between any 2 C

atoms?

A triple bond (3 pairs or 6 electrons)

Properties of hydrocarbon molecules

• Molecular• Low melting points• Low boiling points• Low Hf

• Low Hv

• High evaporation rate• High vapor pressure• May be gases,

liquids, or solids

• Decompose on heating• Poor conductors of

heat & electricity• Nonpolar (vdw forces)• Dissolve in nonpolar

solvents• React slowly• Solids may be soft or

brittle

Bonding capacity of H?

1

Bonding capacity of O?

2

Bonding capacity of the halogens (F, Cl, Br, I)?

1

Bonding capacity of S?

2

Bonding capacity of N & P?

3

Bonding capacity of C?

4

The 4 single bonds of a carbon atom are directed to

…

the corners of a regular tetrahedron.

Saturated hydrocarbon

Hydrocarbon containing only single carbon-

carbon bonds

Unsaturated hydrocarbon

Hydrocarbon containing at least 1 double or triple carbon-carbon

bond

Chemical or Molecular Formulas

Tell the kind & number of atoms in a

molecule.

Structural Formulas

Tell the kind & number of atoms in a molecule. Also

attempt to show approximate shapes & bonding patterns of

molecules.

Homologous Series

A group of related compounds in which each member differs from the one before it by the

same additional unit. Properties vary in a predictable

way.

Alkanes

•Homologous series of saturated hydrocarbons. with the general formula CnH2n+2.

• Ratio of C to H is n:2n+2

Alkanes

Release energy when burned: fuels.

Naming Alkanes

•Prefix: depends on # of carbon atoms in longest continuous chain.

•Suffix: ane

Properties of Alkanes

•Nonpolar.

•Boiling point as # of carbon atoms . (van der Waals forces increase with size).

•Insoluble in water. (Like dissolves like.)

Nonpolar

•The electron cloud of the molecule is fairly evenly distributed. Either:

–Molecule has atoms with similar electronegativities–Molecule has high symmetry

Isomers

•Molecules with the same chemical formula but different structural formulas.

•Different chemical & physical properties. Different names.•Same formula mass & percentage composition.

Isomers

•# of possible isomers as # of C atoms

Alkenes

Homologous series of unsaturated hydrocarbons

containing 1 double carbon-carbon bond.

General formula of alkenes

CnH2n

Naming Alkenes

•Prefix: depends on # of carbon atoms in longest continuous chain.

•Suffix: ene

•# in front may give location of double bond.

Properties of Alkenes

Slightly more reactive than the alkanes. Double bond is site of reactivity.

Alkynes

Homologous series of unsaturated hydrocarbons containing 1 carbon-carbon triple bond.

General formula of alkynes

CnH2n-2

Naming alkynes

•Prefix: depends on # of carbon atoms in longest continuous chain.

•Suffix: yne

•# in front gives location of triple bond.