chapter 20: carbon and hydrocarbons 20.1 – abundance and importance of carbon 20.2 – organic...
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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
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