9 1 Carbon Compounds Carbon compounds form the

9. 1 Carbon Compounds Carbon compounds form the structures of a whale’s cells and control reactions that take place in those cells. The instructions for these processes are stored in organic compounds.

9. 1 Carbon Compounds An organic compound contains carbon and hydrogen, often combined with a few other elements such as oxygen and nitrogen. There are millions of organic compounds—more than 90 percent of all known compounds.

9. 1 Carbon Compounds Carbon has four valence electrons. A carbon atom can form • four single covalent bonds, • a double bond and two single bonds, or • a triple bond a single bond. Most of the bonds in organic compounds are carbonto-carbon bonds or carbon-to-hydrogen bonds.

9. 1 Carbon Compounds Forms of Carbon What are three forms of carbon? Diamond, graphite, and fullerenes are forms of carbon.

9. 1 Carbon Compounds Forms of Carbon Diamond is an example of a network solid, in which all the atoms are linked by covalent bonds. • Covalent bonds connect each carbon atom to four other carbon atoms. • The three-dimensional structure is rigid, compact, and strong. • Diamond is harder than other substances because cutting a diamond requires breaking many covalent bonds.

9. 1 Carbon Compounds Forms of Carbon Graphite is extremely soft and slippery. • Carbon atoms are arranged in widely spaced layers. • Within each layer, carbon atoms form strong covalent bonds with three other carbon atoms. • Between layers the bonds are weak, so layers slide easily past one another.

9. 1 Carbon Compounds Forms of Carbon Fullerenes are large hollow spheres or cages of carbon. On the surface of a 60 -carbon fullerene (C 60), the atoms form alternating hexagons and pentagons. The C 60 molecule is called buckminsterfullerene.

9. 1 Carbon Compounds Forms of Carbon A In diamond, carbon atoms are arranged in a rigid, threedimensional network. B In graphite, the atoms are arranged in layers. C In fullerenes, carbon atoms are arranged in hollow spheres. Diamond Graphite Buckminsterfullerene

9. 1 Carbon Compounds Saturated Hydrocarbons What factors determine the properties of a hydrocarbon? A hydrocarbon is an organic compound that contains only the elements hydrogen and carbon. Factors that determine the properties of a hydrocarbon are the number of carbon atoms and how the atoms are arranged.

9. 1 Carbon Compounds Saturated Hydrocarbons In a saturated hydrocarbon, all of the bonds are single bonds. A saturated hydrocarbon contains the maximum possible number of hydrogen atoms for each carbon atom. Saturated hydrocarbons are also called alkanes. Their names end in –ane.

9. 1 Carbon Compounds Saturated Hydrocarbons A hydrocarbon molecule can contain one carbon atom, as in methane, or more than 30 carbon atoms, as in asphalt. The carbon atoms can be arranged in a straight chain, a branched chain, or a ring.

9. 1 Carbon Compounds Saturated Hydrocarbons Microorganisms in the stomachs of a cow produce more than 500 liters of methane (CH 4) per day.

9. 1 Carbon Compounds Saturated Hydrocarbons Straight Chains • A molecular formula shows the type and number of atoms in a molecule of the compound. • A structural formula shows how those atoms are arranged. • The boiling point of a straight-chain alkane depends on the number of carbon atoms. Methane and propane are gases at room temperature. Pentane and octane are liquids.

9. 1 Carbon Compounds Saturated Hydrocarbons

9. 1 Carbon Compounds Saturated Hydrocarbons Branched Chains Butane and isobutane both have a molecular formula of C 4 H 10, but their structural formulas are different.

9. 1 Carbon Compounds Saturated Hydrocarbons Compounds with the same molecular formula but different structural formulas are isomers. • In isobutane, there is a branch at the point where a carbon atom bonds to three other carbon atoms. • Differences in structure affect some properties of isomers. Butane boils at – 0. 5°C, but isobutane boils at – 11. 7°C.

9. 1 Carbon Compounds Saturated Hydrocarbons Rings Carbon atoms in cyclobutane are linked in a fourcarbon ring.

9. 1 Carbon Compounds Saturated Hydrocarbons In a cycloalkane, each carbon atom forms bonds with two other carbon atoms and two hydrogen atoms. • So cyclobutane (C 4 H 8) molecules have two fewer hydrogen atoms than butane (C 4 H 10) molecules. • Most ring alkanes, or cyclic hydrocarbons, have rings with five or six carbons.

9. 1 Carbon Compounds Unsaturated Hydrocarbons What are three types of unsaturated hydrocarbons? A hydrocarbon that contains one or more double or triple bonds is an unsaturated hydrocarbon. There are three types of unsaturated hydrocarbons—alkenes, alkynes, and aromatic hydrocarbons.

9. 1 Carbon Compounds Unsaturated Hydrocarbons Alkenes There is a double bond between the two carbon atoms in ethene. Hydrocarbons that have one or more carbon-carbon double bonds are alkenes. The names of alkenes end in –ene.

9. 1 Carbon Compounds Unsaturated Hydrocarbons Many fruit-bearing plants produce ethene (C 2 H 4), which controls the rate at which fruits, such as this tomato, ripen.

9. 1 Carbon Compounds Unsaturated Hydrocarbons Alkynes Ethyne (C 2 H 2) is an alkyne. Alkynes are straightor branched-chain hydrocarbons that have one or more triple bonds. Alkyne names end in –yne.

9. 1 Carbon Compounds Unsaturated Hydrocarbons Alkynes are the most reactive hydrocarbon compounds. Ethyne (C 2 H 2), also known as acetylene, is used in torches that cut metal or weld them together.

9. 1 Carbon Compounds Unsaturated Hydrocarbons Aromatic Hydrocarbons Benzene (C 6 H 6) is an unsaturated hydrocarbon with a ring structure.

9. 1 Carbon Compounds Unsaturated Hydrocarbons Although the formula for Benzene shows alternating single and double bonds, the six bonds in the ring are identical. All six carbon atoms share six of the valence electrons. Hydrocarbons that contain similar ring structures are known as aromatic hydrocarbons. The name was chosen because many of these compounds have strong aromas, or odors.

9. 1 Carbon Compounds Fossil Fuels What are three main fossil fuels? Three types of fossil fuels are coal, natural gas, and petroleum. Fossil fuels are mixtures of hydrocarbons that formed from the remains of plants or animals.

9. 1 Carbon Compounds Fossil Fuels Coal • Giant tree ferns and other plants were buried in swamps. • After millions of years of pressure, the plant remains produced a mixture of hydrocarbons. • Most of the hydrocarbons in coal are aromatic hydrocarbons with high molar masses. • Coal produces more soot than other fossil fuels.

9. 1 Carbon Compounds Fossil Fuels The ferns shown are similar to ferns that lived millions of years ago. Imprints of ferns in coal are evidence that coal formed when plant remains were compressed.

9. 1 Carbon Compounds Fossil Fuels Natural Gas • Natural gas formed from the remains of marine organisms. • The main component of natural gas is methane. Natural gas also contains ethane, propane, and isomers of butane. • Natural gas is used for heating and cooking. • Deposits of natural gas are found along with coal and petroleum.

9. 1 Carbon Compounds Fossil Fuels Petroleum • Petroleum also formed from marine organisms. • Petroleum is pumped from deep beneath Earth’s surface. • Petroleum is a complex liquid mixture of hydrocarbons, mainly long-branched alkanes and alkenes.