Section 1 Compounds of Carbon• Explain the unique properties of carbon that make the formation of organic molecules possible.• Relate the structures of diamond, graphite, and other allotropes of carbon to their properties.• Describe the nature of the bonds formed by carbon in alkanes, alkenes, alkynes, aromatic compounds,

and cyclic compounds.• Classify organic compounds such as alcohols, esters, and ketones by their functional groups.• Explain how the structural difference between isomers is related to the difference in their properties.

Properties of Carbon• Carbon atoms nearly always form covalent bonds.• Three factors make carbon-carbon bonds unique:

• First, carbon-carbon bonds are quite strong• Second, carbon compounds are not very reactive. • Third, carbon can form up to four single covalent bonds, so a wide variety of compounds is

possible.Carbon Exists in Different Allotropes

• As an element, carbon atoms can form different bonding arrangements, or allotropes.• The different allotropes have properties that differ due to the different arrangements of the carbon bonds.

Other Carbon Allotropes Include Fullerenes and Nanotubes• Besides diamond and graphite, carbon allotropes include buckminsterfullerene, and nanotubes.

Organic Compounds• Organic compounds contain carbon, and most also contain atoms of hydrogen.• They can contain other elements, such as oxygen, nitrogen, sulfur, phosphorus, and the halogens. • Chemists group organic compounds with similar characteristics into classes.• The simplest class of organic compounds, hydrocarbons, contain only carbon and hydrogen.

Alkanes Are the Simplest Hydrocarbons• Alkanes are hydrocarbons with carbon atoms that are connected only by single bonds.• Three alkanes are methane, ethane, and propane.• The formulas of the alkanes fit the general formula CnH2n+2, where n is the number of carbon atoms.

• For example, if an alkane has 30 carbon atoms, then its formula is C30H62.Many Hydrocarbons Have Multiple Bonds

• Alkenes are hydrocarbons that contain at least one double bond between two carbon atoms. • Alkenes with one double bond have a general formula that is written CnH2n.• Alkynes are hydrocarbons that contain at least one triple bond between two carbon atoms.• An alkyne with one triple bond is written as CnH2n−2.

Carbon Atoms Can Form Rings• Carbon atoms that form covalent bonds with one another can be arranged in a straight line or in a

branched arrangement.• Carbon bonds can also be arranged in a ring structure.• The prefix cyclo- is added to the name of an alkane to indicate that it has a ring structure.

Benzene Is an Important Ring Compound• An important organic ring compound is the hydrocarbon benzene, C6H6.• Benzene is the simplest aromatic hydrocarbon.• It can be drawn as a ring with three double bonds.• Experiments show that all the carbon-carbon bonds in benzene are the same, so it is a molecule with

resonance structures.Other Organic Compounds

• Other classes of organic compounds contain other atoms such as oxygen, nitrogen, sulfur, phosphorus, and the halogens along with carbon and hydrogen.

• The word organic originally described only compounds made by living things. Now chemists can make organic compounds from inorganic substances.

Many Compounds Contain Functional Groups• A typical organic compound has a group of atoms that is responsible for its chemical properties.

• This a group of atoms is known as a functional group.• Organic compounds are commonly classified by the functional groups they contain.• Because single bonds between carbon atoms rarely react, functional groups are often responsible for

how an organic compound reacts.Functional Groups Determine Properties

• The presence of a functional group causes an organic compound to have properties that differ greatly from those of the corresponding hydrocarbon.

• The structural formulas of butane and 1-butanol both have 4 carbon atoms joined by single bonds in a line.

• Butane is a gas at room temperature, but 1-butanol is a liquid and has a greater density and higher melting and boiling points than butane.

• The only difference between butane and 1-butanol is the presence of the functional group —OH on one of the carbon atoms in 1-butanol.

Different Isomers Have Different Properties• Both molecules below are alcohols and have the same molecular formula: C4H10O.• The molecules of 1-butanol and 2-methyl-1-propanol differ in the way in which their atoms are

arranged.• Isomers are compounds that have the same formula but differ in their chemical and physical properties

because of the difference in the arrangement of their atoms.• The greater the structural difference between two isomers, the more they will differ in their properties.

Section 2 Names and Structures of Organic CompoundsObjectives

• Name simple hydrocarbons from their structural formulas.• Name branched hydrocarbons from their structural formulas.• Identify functional groups from a structural formula, and assign names to compounds containing

functional groups.• Draw and interpret structural formulas and skeletal structures for common organic compounds.

Naming Straight-Chain Hydrocarbons• Inorganic carbon compounds are named by using a system of prefixes and suffixes.• Organic compounds have their own system of prefixes and suffixes that denote classes.

• For example, the names of all alkanes end with the suffix -ane.• For alkanes that consist of five or more carbon atoms, the prefix comes from a Latin word that indicates

the number of carbon atoms in the chain.Naming Short-Chain Alkenes and Alkynes

• A saturated hydrocarbon is one in which each carbon atom forms four single covalent bonds.• The alkanes are saturated hydrocarbons.

• An unsaturated hydrocarbon is one in which not all carbon atoms have four single covalent bonds.• Alkenes and alkynes are unsaturated hydrocarbons.

• The rules for naming an unsaturated hydrocarbon with fewer than four carbon atoms are similar to those for naming alkanes.

• A two-carbon alkene is named ethene, with the suffix -ene indicating that the molecule is an alkene.

• A three-carbon alkyne is named propyne, with the suffix –yne indicating that the molecule is an alkyne.

Naming Long-Chain Alkenes and Alkynes• The name for an unsaturated hydrocarbon containing four or more carbon atoms must indicate the

position of the double or triple bond within the molecule.• First number the C atoms in the chain so that the first C atom in the double bond has the lowest number.• If there is more than one multiple bond in a molecule, number the position of each multiple bond, and

use a prefix to indicate the number of multiple bonds.• The molecules on the left is correctly numbered from left to right because the first carbon atom with the

double bond must have the lowest number.

• For example, the following molecule is called 1,3-pentadiene.

• (Note the placement of the prefix di-.)Naming Branched Hydrocarbons

• When a hydrocarbon is not a simple straight chain, first count the carbon atoms in the longest chain.• The named is based on the corresponding alkane. The compound below has a “parent” chain that

contains 7 carbon atoms, so it is heptane.

• Next, number the C atoms so that any branches on the chain have the lowest numbers possible.Name the Attached Groups and Indicate Their Positions

• The third carbon atom has a —CH3 group attached. This group is known as a methyl group.• Because the methyl group is attached to the third C, the complete name is 3-methylheptane.• You can omit the numbers if there is no possibility of ambiguity.

• For example, a propane chain can have a methyl group only on its second carbon.• If the methyl group were on the first or third carbon of propane, the molecule would be butane.• So, 2-methylpropane is called methylpropane.

• With unsaturated hydrocarbons that have attached groups, the longest chain containing the double bond is considered the parent compound.

• In addition, if more than one group is attached to the longest chain, the position of attachment of each group is given.

• Prefixes are used if the same group is attached more than once.

• The chain with the double bond has 5 C atoms, so the compound is a pentene.• The 1st C atom has a double bond, so it is 1-pentene. Two methyl groups are attached to the third carbon

atom, so the name is 3,3-dimethyl-1-pentene.Naming a Branched HydrocarbonSample Problem AName the following hydrocarbon.Names of Compounds Reflect Functional Groups

• Names for organic compounds with functional groups are based on the same system for branched chains.

• First, the longest chain is named.• Then a prefix or suffix indicating the functional group is added to the hydrocarbon name. • When necessary, the position of the functional group is noted just as with hydrocarbon branches.

Naming Compounds with Functional Groups• A prefix or suffix can indicate a functional group.• Because the longest chain in the structure below has three C atoms, the name is based on propane.

• The —OH functional group classifies it as an alcohol.• Because the —OH is attached to the second C atom, the correct name for this compound is 2-propanol.

Sample Problem BName the following organic compound.

Representing Organic Molecules• There are many ways of depicting organic molecules.• Each type of model used to represent an organic compound has both advantages and disadvantages. • They can highlight different features such as the number and kinds of atoms or the three-dimensional

shape of the space-filling model.• A model cannot fully show the true three-dimensional shape of a molecule or show the motion within a

molecule caused by the atoms’ constant vibration.Structural Formulas Can Be Simplified

• Structural formulas are sometimes represented by skeletal structures, which show bonds, but leave out some or even all of the carbon and hydrogen atoms.

• Skeletal structures usually show the carbon framework only as lines representing bonds.• These lines form a zigzag pattern to indicate the tetrahedral arrangement of bonds.• Atoms other than C and H are always shown.• In structural formulas, C and H atoms are not shown unless they are part of functional groups.

Sample Problem CDraw both the structural formula and the skeletal structure for 1,2,3-propanetriol. Section 3 Organic ReactionsObjectives

• Describe and distinguish between substitution and addition reactions.• Describe and distinguish between condensation and elimination reactions.

Substitution and Addition Reactions• Organic compounds participate in a variety of chemical reactions.• A substitution reaction is a reaction in which one or more atoms replace another atom or group of

atoms in a molecule. • An addition reaction is a reaction in which an atom or molecule is added to an unsaturated molecule

and increases the saturation of the molecule.Halogens Often Replace Hydrogen Atoms

• One substitution reaction occurs when a halogen, such as a chlorine atom, replaces a hydrogen atom on an alkane molecule, such as methane.

• The substitution reactions can continue, replacing the remaining H atoms in methane one at a time.• The products are dichloromethane, trichloromethane, and tetrachloromethane (commonly known as

chloroform).Hydrogenation Is a Common Addition Reaction

• One addition reaction is hydrogenation, in which H atoms are added to an unsaturated molecule.

• The product of the reaction contains fewer double or triple bonds than the reactant.Making Consumer Products by Hydrogenation

• Another kind of hydrogenation is the manufacture of cyclohexane from benzene as shown below.

• Over 90% of the cyclohexane that is made is used in the manufacture of nylon.Some Addition Reactions Form Polymers

• Some addition reactions involve joining smaller molecules together to make larger ones.• The smaller molecules are known as monomers.• The larger molecule that is made by the addition reaction is called a polymer.• Polyethylene is a strong but flexible plastic that is made from ethane monomers, C2H4. • Because ethene is commonly known as ethylene, the polymer it forms is often called polyethylene. • The following equation shows how a portion of the polymer forms.

Monomers Can Be Added in Different Ways• Polyethylene is a very long alkane polymer chain.• The chains form a product that is strong yet flexible.• Monomers can be added so that a chain branches.

• For example, an ethene monomer is sometimes added to form a side chain.• A polymer with many side chains remain flexible.

Condensation and Elimination• Polymers can also be formed by a condensation reaction in which two molecules combine, usually

accompanied by the loss of a water molecule.• The formation of water as a reaction product is the reason for the name of this type of reaction.• An elimination reaction is a reaction in which a simple molecule is removed from adjacent carbon

atoms on the same organic molecule.• An elimination reaction also produces water.

Condensation Reactions Produce Nylon• Nylon is formed in a condensation reaction.• The reaction takes place between an amine group on hexanediamine and a carboxyl group on adipic

acid.• A water molecule is eliminated when an H atom from the amine group and an —OH group from the

carboxyl group are removed.• This reaction repeats, linking hundreds of reactantsto form the synthetic polymer called nylon 66.

Many Polymers Form by Condensation Reactions• The polymer polyethylene terephthalate, abbreviated PET, is formed when two monomers are combined

in the following condensation reaction.

• The functional group present in the product shown above classifies this molecule as an ester, so PET is a polyester.

Elimination Reactions Often Form Water

• The acid catalyzes a reaction that eliminates water from ethanol, which leaves a double bond.