Page 341 - 9780077418427.pdf

/Users/user-f465/Desktop
tiL12214_ch12_299-322.indd Page 318 9/3/10 6:13 PM user-f465
tiL12214_ch12_299-322.indd Page 318 9/3/10 6:13 PM user-f465 /Users/user-f465/Desktop

SUMMARY

Organic chemistry is the study of compounds that have carbon as the The monosaccharides are simple sugars such as glucose and fructose.
principal element. Such compounds are called organic compounds, and Glucose is blood sugar, a source of energy. The disaccharides are su-
all the rest are inorganic compounds. There are millions of organic com- crose (table sugar), lactose (milk sugar), and maltose (malt sugar).
pounds because a carbon atom can link with other carbon atoms as The disaccharides are broken down (digested) to glucose for use by
well as atoms of other elements. the body. The polysaccharides are polymers of glucose in straight or
A hydrocarbon is an organic compound consisting of hydrogen branched chains used as a near-term source of stored energy. Plants
and carbon atoms. The simplest hydrocarbon is one carbon atom and store the energy in the form of starch, and animals store it in the
four hydrogen atoms, or CH 4 . All hydrocarbons larger than CH 4 have form of glycogen. Cellulose is a polymer similar to starch that humans
one or more carbon atoms bonded to another carbon atom. The bond cannot digest.
can be single, double, or triple, and this forms a basis for classifying Fats and oils are esters formed from three fatty acids and glycerol
hydrocarbons. A second basis is whether the carbons are in a ring into a triglyceride. Fats are usually solid triglycerides associated with
or not. The alkanes are hydrocarbons with single carbon-to- carbon animals, and oils are liquid triglycerides associated with plant life, but
bonds, the alkenes have a double carbon-to-carbon bond, and the al- both represent a high-energy storage material.
kynes have a triple carbon-to-carbon bond. The alkanes, alkenes, and Polymers are huge, chainlike molecules of hundreds or thousands
alkynes can have straight- or branched-chain molecules. When the of smaller, repeating molecular units called monomers. Polymers occur
number of carbon atoms is greater than three, there are different ar- naturally in plants and animals, and many synthetic polymers are made
rangements that can occur for a particular number of carbon atoms. today from variations of the ethylene-derived monomers. Among the
The different arrangements with the same molecular formula are called more widely used synthetic polymers derived from ethylene are poly-
isomers. Isomers have different physical properties, so each isomer is ethylene, polyvinyl chloride, polystyrene, and Teflon. Problems with the
given its own name. synthetic polymers include that (1) they are manufactured from fossil
The alkanes have all the hydrogen atoms possible, so they are satu- fuels that are also used as the primary energy supply, and (2) they do not
rated hydrocarbons. The alkenes and the alkynes can add more hydro- readily decompose and tend to accumulate in the environment.
gens to the molecule, so they are unsaturated hydrocarbons. Unsaturated
hydrocarbons are more chemically reactive than saturated molecules.
Hydrocarbons that occur in a ring or cycle structure are cyclohy- KEY TERMS
drocarbons. A six-carbon cyclohydrocarbon with three double bonds
has different properties than the other cyclohydrocarbons because the alkane (p. 301)
double bonds are not localized. This six-carbon molecule is benzene, alkene (p. 302)
the basic unit of the aromatic hydrocarbons. alkyne (p. 304)
Petroleum is a mixture of alkanes, cycloalkanes, and a few aro- amino acids (p. 311)
matic hydrocarbons that formed from the slow decomposition of bur- aromatic hydrocarbons (p. 305)
ied marine plankton and algae. Petroleum from the ground, or crude carbohydrates (p. 312)
oil, is distilled into petroleum products of natural gas, LPG, petroleum cellulose (p. 313)
ether, gasoline, kerosene, diesel fuel, and motor oils. Each group contains disaccharides (p. 312)
a range of hydrocarbons and is processed according to use. fat (p. 314)
In addition to oxidation, hydrocarbons react by substitution, functional group (p. 307)
addition, and polymerization reactions. Reactions take place at sites hydrocarbon (p. 300)
of multiple bonds or lone pairs of electrons on the functional groups. hydrocarbon derivatives (p. 307)
The functional group determines the chemical properties of organic inorganic chemistry (p. 300)
compounds. Functional group results in the hydrocarbon derivatives isomers (p. 302)
of alcohols, ethers, aldehydes, ketones, organic acids, esters, and amines. macromolecule (p. 311)
Living organisms have an incredible number of highly orga nized monosaccharides (p. 312)
chemical reactions that are catalyzed by enzymes, using food and energy oil (p. 314)
to grow and reproduce. The process involves building large macro- organic chemistry (p. 300)
molecules from smaller molecules and units. The organic molecules petroleum (p. 305)
involved in the process are proteins, carbohydrates, and fats and oils. polymer (p. 307)
Proteins are macromolecular polymers of amino acids held polysaccharides (p. 312)
together by peptide bonds. There are 20 amino acids that are used proteins (p. 311)
in various polymer combinations to build structural and functional starches (p. 312)
proteins. Structural proteins are muscles, connective tissue, and the triglyceride (p. 314)
skin, hair, and nails of animals. Functional proteins are enzymes,
hormones, and antibodies.
Carbohydrates are polyhydroxyl aldehydes and ketones that form
three groups: the monosaccharides, disaccharides, and polysaccharides.

318 CHAPTER 12 Organic Chemistry 12-20