1. Section 4: Organic compounds
1.1. The Four Bonds of a Carbon Atom
1.1.1. Carbon Backbones: Models called called structural formulas are used to show how atoms in a molecule are connected. Each line represents a pair of electrons that form a covalent bond.
1.2. Hydrocarbons and Other Organic Compounds
1.2.1. Saturated Hydrocarbons: A saturated hydrocarbon, or alkane, is a hydrocarbon in which each carbon atom in the molecule shares a single bond with each of four other atoms.
1.2.2. Unsaturated Hydrocarbons: An unsaturated hydrocarbon, such as ethene or ethyne, is a hydrocarbon in which at least one pair of carbon atoms shares a double bond or a triple bond.
1.2.3. Aromatic Hydrocarbons: Most aromatic (AR uh MAT ik) compounds are based on benzene. As shown in Figure 3, benzene has a ring of six carbons that have alternating double and single bonds.
1.2.4. Other Organic Compounds: There are many other kinds of organic compounds. Some have atoms of halogens, oxygen, sulfur, and phosphorus in their molecules.
1.3. Biochemicals: The Compounds of Life
1.3.1. Carbohydrates: Carbohydrates are biochemicals that are composed of one or more simple sugar molecules bonded together. Carbohydrates are used as a source of energy. There are two kinds of carbohydrates: simple carbohydrates and complex carbohydrates.
1.3.2. Lipids: Lipids are biochemicals that do not dissolve in water. Fats, oils, and waxes are kinds of lipids. Lipids have many functions, including storing energy and making up cell membranes.
1.3.3. Proteins: Most of the biochemicals found in living things are proteins. In fact, after water, proteins are the most common molecules in your cells. Proteins are biochemicals that are composed of “building blocks” called amino acids.
1.3.4. Nucleic Acids: The largest molecules made by living organisms are nucleic acids. Nucleic acids are biochemicals made up of nucleotides (NOO klee oh TIEDZ). Nucleotides are molecules made of carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms.
1.3.5. DNA and RNA: There are two kinds of nucleic acids: DNA and RNA. DNA is the genetic material of the cell. DNA molecules can store a huge amount of information because of their length. When a cell needs to make a certain protein, it copies a certain part of the DNA. The information copied from the DNA directs the order in which amino acids are bonded to make that protein. DNA also contains information used to build the second type of nucleic acid, RNA, which is involved in the actual building of proteins.
2. Section 1: Ionic and Covalent Bonds
2.1. Ionic Compounds and Their Properties
2.1.1. Brittleness: Ionic compounds tend to be brittle at room temperature.
2.1.2. High Melting Points: Ionic compounds have high melting because of the strong ionic bonds that hold ions together.
2.1.3. Solubility and Electrical Conductivity: Many ionic compounds are highly soluble. Therefore they dissolve easily in water. Water molecules attract each of the ions of an ionic compound and pull the ions away from one another.
2.2. Covalent Compounds and Their Properties
2.2.1. Low Solubility: Many covalent compounds are not soluble in water, which means that they do not dissolve well in water.
2.2.2. Low Melting Points: The forces of attraction between molecules of covalent compounds are much weaker than the bonds holding ionic solids together. Less heat is needed to separate the molecules of covalent compounds.
2.2.3. Electrical Conductivity: Although most covalent compounds don’t dissolve in water, some do. Most of the covalent compounds that dissolve in water form solutions that have uncharged molecules.
3. Section 2: Acids and Bases
3.1. Acids and Their Properties
3.1.1. Acids Have a Sour Flavor: Have you ever taken a bite of a lemon or lime? If so, like the boy in Figure 1, you know the sour taste of an acid. The taste of lemons, limes, and other citrus fruits is a result of citric acid.
3.1.2. Acids Change Colors in Indicators: A substance that changes color in the presence of an acid or base is an indicator.
3.1.3. Acids React with Metals: Acids react with some metals to produce hydrogen gas.
3.1.4. Acids Conduct Electric Current: When acids are dissolved in water, they break apart and form ions in the solution. The ions make it possible for the solution to conduct an electric current.
3.1.5. Uses of Acids: Acids are used in many areas of industry and in homes. Sulfuric acid is the most widely made industrial chemical in the world. It is used to make many products, including paper, paint, detergents, and fertilizers.
3.2. Bases and Their Properties
3.2.1. Bases Have a Bitter Flavor and a Slippery Feel: The properties of a base solution include a bitter taste and a slippery feel.
3.2.2. Bases Change Color in Indicators: Like acids, bases change the color of an indicator. Most indicators turn a different color in the presence of bases than they do in the presence of acids.
3.2.3. Bases Conduct Electric Current: Solutions of bases conduct an electric current because bases increase the number of hydroxide ions, OH–, in a solution.
3.2.4. Uses of Bases: Like acids, bases have many uses. Sodium hydroxide is a base used to make soap and paper. It is also used in oven cleaners and in products that unclog drains.
4. Section 3: Solutions of Acids and Bases
4.1. Strengths of Acids and Bases
4.1.1. Strong Versus Weak Acids: As an acid dissolves in water, the acid’s molecules break apart and produce hydrogen ions, H+. If all of the molecules of an acid break apart, the acid is called a strong acid. Strong acids include sulfuric acid, nitric acid, and hydrochloric acid. If only a few molecules of an acid break apart, the acid is a weak acid. Weak acids include acetic (uh SEET ik) acid, citric acid, and carbonic acid.
4.1.2. Strong Versus Weak Bases: When all molecules of a base break apart in water to produce hydroxide ions, OH–, the base is a strong base. Strong bases include sodium hydroxide, calcium hydroxide, and potassium hydroxide. When only a few molecules of a base break apart, the base is a weak base, such as ammonium hydroxide and aluminum hydroxide.
4.2. Acids, Bases, and Neutralization
4.2.1. The pH Scale: An indicator, such as litmus, can identify whether a solution contains an acid or base. To describe how acidic or basic a solution is, the pH scale is used. A solution that has a pH of 7 is neutral, which means that the solution is neither acidic nor basic.
4.2.2. Using Indicators to Determine pH: A combination of indicators can be used to find out how basic or how acidic a solution is. This can be done if the colors of the indicators are known at different pH values.
4.2.3. pH and the Environment: Living things depend on having a steady pH in their environment.
4.3. Salts
4.3.1. Uses of Salts: Salts have many uses in industry and in homes.