Chapter 24: Organic Compounds

Section 1: Simple Organic Compounds

  • Organic Compounds   * Most compounds containing the element carbon   * A carbon atom has four electrons in its outer energy level   * Another reason carbon can form so many compounds is that carbon can link together with other carbon atoms in many different arrangements—chains, branched chains, and even rings.   * Hydrocarbon: A compound made up of only carbon and hydrogen atoms
  • Carbon forms an enormous number of compounds with hydrogen alone.
  • The structural formula uses lines to show that four hydrogen atoms are bonded to one carbon atom in a methane molecule.
  • The space-filling model, shows a more realistic picture of the relative size and arrangement of the atoms in the molecule.
  • Methane and other hydrocarbons produce more than 90 percent of the energy humans use.
  • Single Bonds   * In some hydrocarbons, the carbon atoms are joined by single covalent bonds.   * Saturated Hydrocarbons: Hydrocarbons containing only single-bonded carbon atoms.   * The chemical formula of butane is C4H10. Another hydrocarbon called isobutane has exactly the same chemical formula.   * Boiling points of hydrocarbons increase as the

    number of carbon atoms in the chain increases.   * Isomers: compounds that have identical chemical formulas but different molecular structures and shapes.   * Thousands of isomers exist among the hydrocarbons.   * Some isomers differ only slightly in how their atoms are arranged in space.

  • Multiple Bonds   * Ethylene is another name for the hydrocarbon ethene, C2H4. This contains one double bond in which two carbon atoms share two pairs of electrons.   * Unsaturated Hydrocarbons: Hydrocarbons, such as ethene and ethyne, that contain at least one double or triple bond.

Section 2: Other Organic Compounds

  • Aromatic Compounds   * Many chemical compounds produce pleasant odors but others have less pleasant flavors and smells.   * Aromatic Compound: one that contains a benzene structure having a ring with six carbons.   * Many known compounds contain three or more rings fused together.
  • Substituted Hydrocarbons: changed compounds   * Chemists change hydrocarbons into other compounds having different physical and chemical properties.   * A substituted hydrocarbon has one or more of its hydrogen atoms replaced by atoms or groups of other elements.   * Alcohol: formed when –OH groups replace one or more hydrogen atoms in a hydrocarbon.   * Organic acids form when a carboxyl group, –COOH, is substituted for one of the hydrogen atoms attached to a carbon atom.   * Other atoms besides hydrogen and oxygen can be added to hydrocarbons. One is chlorine.   * When sulfur replaces oxygen in the –OH group of an alcohol, the resulting compound is called a thiol, or more commonly a mercaptan.

Section 3: Petroleum—A Source of Carbon Compounds

  • What is petroleum?   * Petroleum—a dark, flammable liquid, often called crude oil, that is found deep within Earth.   * Like coal and natural gas, this dark, foul-smelling substance is formed from the remains of

    fossilized material.   * The separation process is known as fractional distillation.   * The tower separates crude oil into fractions containing compounds having a range of boiling points.   * The higher boiling fractions reach only the lower plates before they condense, forming shallow pools that drain off through pipes on the sides of the tower and are collected.   * The separation of the fractions is improved by the inter- action of rising vapors with condensed liquid. The processes involved vary.

  • Uses for Petroleum Compounds   * The fractions that condense on the upper plates and contain from five to ten carbons are used for gasoline and solvents.   * Some fractions are used directly for fuel—the lightest fractions from the top of the tower include butane and propane.
  • Polymers: Extremely large molecules   * Monomer: small molecule, which forms a link in the polymer chain   * One common polymer or plastic is made from the monomer ethene or ethylene.   * Polyethylene: ethylene combines with itself repeatedly.   * Polymers can be made light and flexible or so strong that they can be used to make plastic pipes, boats, and even some auto bodies.   * The properties of polymers depend mostly on which monomers are used to make them.   * Polymer materials can be shaped in many ways.   * Sometimes the same polymer can take two completely different forms.   * Other polymers can be spun into threads, which are used to make clothing or items such as suitcases and backpacks.   * The first synthetic dye was a bright purple called mauve that was discovered accidentally in coal tar compounds.   * Polymers have been used so widely that disposal has caused problems, because many polymers do not decompose.   * Depolymerization: uses heat or chemicals to break the long polymer chain into its monomer fragments.

Section 4: Biological Compounds

  • Biological Polymers   * Like the polymers that are used to make the plastics and fibers, biological polymers are huge molecules.   * Many of the important biological compounds in your body are polymers. Among them are the proteins, which often contain hundreds of units.
  • Proteins: large organic polymers formed from organic monomers called amino acids.   * Amino acids are the monomers that combine to form proteins.   * Amine groups of one amino acid can combine with the carboxylic acid group of another amino acid, linking them together to form a compound called a peptide.   * Long protein molecules tend to twist and coil in a manner unique to each protein.   * When you eat foods that contain proteins, such as meat, dairy products, and some vegetables, your body breaks down the proteins into their amino acid monomers.
  • Nucleic Acids: another important group of organic polymers that are essential for life.
  • Deoxyribonucleic Acid: or DNA, is found in cells where it codes and stores genetic information. This is known as the genetic code.   * The monomers that make up DNA are called nucleotides. A nucleotide is a complex molecule that contains one of four organic bases, a sugar, and a phosphate unit.   * Human DNA contains more than 5-billion base pairs.   * The DNA of each person differs in some way from that of everyone else, except for identical twins, who share the same DNA sequence.
  • Carbohydrates: compounds containing carbon, hydrogen, and oxygen, that have twice as many hydrogen atoms as oxygen atoms.   * Sugars are a major group of carbohydrates.   * The sugar glucose is found in your blood and also in many sweet foods such as grapes and honey. Starch is a carbohydrate that is also a polymer.   * It is made of units or monomers of the sugar glucose.
  • Lipids: Fats, oils, and related compounds make up a group of organic compounds   * Lipids include animal fats such as butter, and vegetable oils such as corn oil.   * Saturated fats contain only single bonds between carbon atoms.
  • Unsaturated fats having one double bond are called monounsaturated, and those having two or more double bonds are called polyunsaturated.   * Plant lipids called oils are unsaturated and are usually liquids.   * It appears that saturated fats are more likely to be converted to substances that can block the arteries leading to the heart.   * Cholesterol is another lipid that is often in the news. It is found in meats, eggs, butter, cheese, and fish.

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