Chapter 20: Carbon and Hydrocarbons

20.1 – Abundance and Importance of Carbon

20.2 – Organic Compounds 20.3 – Saturated Hydrocarbons 20.4 – Unsaturated Hydrocarbons

Structure and Bonding of Carbon Carbon, the first member of Group 14, has

mostly nonmetallic properties. Carbon atoms tend to form four single bonds. This bonding results in a tetrahedral shape.

Allotropes of Carbon Carbon occurs in several solid allotropic forms

that have dramatically different properties. Diamond – Colorless, crystalline, solid form of

carbon Graphite – soft, black, crystalline form of carbon

that is a fair conductor of electricity. Fullerenes – dark colored solids made of

spherically networked carbon atom cages

Allotropes of Carbon - Diamond The hardest material

known to man Carbon atoms are bonded

covalently in a network fashion

Conducts heat 5x better than silver or copper

Does not conduct electricity

Allotropes of Carbon - Graphite Soft, crumbles easily

and feels greasy Used as a lubricant

and as lead Good conductor of

electricity Stronger and lighter

than steel

Allotropes of Carbon - Fullerenes Discovered in the

1980s (N.P. 1996) Structure consists of

near spherical cages Scientists are

currently trying to find practical uses for these substances

Organic Compounds Covalently bonded compounds containing

carbon, excluding carbonates and oxides

The diversity of organic compounds results from the uniqueness of carbon’s structure and bonding

Carbon – Carbon Bonding Catenation – Carbon atoms are unique in

their ability to form long chains and rings of covalently bonded atoms.

Carbon Bonding to Other Elements Hydrocarbons – composed of only carbon

and hydrogen; they are the simplest organic compounds.

Most contain hydrocarbon backbones and have other elements added on (O, S, and N)

Arrangement of Atoms Isomer – Compounds that have the same

molecular formula but different structures

As the number of carbons increases so does the number of possible isomers

Structural Formula Indicates the number and types of atoms

present in a molecule and also shows the bonding arrangement of the atoms

Structural formulas do not accurately represent the three dimensional shape of the molecule.

Isomers – Structural Structural Isomers – isomers in which the

atoms are bonded together in different orders

Isomers - Geometric Isomers in which the order of atom

bonding is the same but the arrangement of atoms in space is different

In order for geometric isomers to exist, there must be a rigid structure in the molecule to prevent free rotation around a bond

Cis and Trans

Saturated Hydrocarbons Hydrocarbons in which each carbon atom

in the molecule form four single covalent bonds with other atoms

Alkanes CnH2n+2

Hydrocarbons that contain only single bonds

Homologous series – one in which adjacent members differ by a constant unit.

Alkyl groups- groups of atoms that are formed when one hydrogen atom is removed from an alkane molecule

Cycloalkanes Alkanes in which the carbon atoms are

arranged in a ring, or cyclic, structure

Alkane NomenclatureUnbranched Chain

Count the longest continuous chain.

Use greek prefix (at right)

End with -ane

Alkane NomenclatureBranched Chain

Name the longest chain (See previous)

Add the name of the alkyl group

Insert position numbers

Punctuate

Example

Cycloalkane Nomenclature Name the longest chain Add Cyclo- Add names of alkyl groups Number the carbons (lowest numbers) Inset position numbers Punctuate

Example Give the name of the following molecule

6 carbons = hexane CH3 = methyl

Number around the circle 1,3 - dimethlycyclohexane

Example Draw 1,1- dimethylcyclobutane

Unsaturated Hydrocarbons Hydrocarbons in which not all carbon

atoms have four single covalent bonds

Alkenes CnH2n

Hydrocarbons that contain double covalent bonds

Alkene Nomenclature Name the same as Alkane Locate the longest continuous chain that

contains the double bond(s). Double bond should have lowest number

Example

Alkynes CnH2n-2

Hydrocarbons with triple covalent bonds

Named the same as others Find the longest chain containing a triple

bond Number so triple bond has lowest number

Example Name the following

Aromatic Hydrocarbons Hydrocarbons with six membered carbon

rings and delocalized electrons Benzene – the primary aromatic

hydrocarbon

Aromatic Nomenclature Name the parent Hydrocarbon (Usually

benzene) Name the Alkyl groups Number the carbon atoms Insert position numbers Add Punctuation

Example Name the following

Example