The links at left lead to additional resources to help you with this chapter. These include Hot Links to Web sites related to the topics in this chapter, the Take It to the Net activities referred to in your textbook, and a Self-Test you can use to test your knowledge of this chapter.
Science News topics pages correlate recently published articles to the topics you are studying.
Section 2-1: The Nature of Matter
The subatomic particles that make up atoms are protons, neutrons, and electrons.
Because they have the same number of protons, all isotopes of an element have the same chemical properties.
The main types of chemical bonds are covalent bonds and ionic bonds.
Section 2-2: Properties of Water
A water molecule is polar, because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.
Acidic solutions contain higher concentrations of H+ ions than pure water and have pH values below 7.
Basic, or alkaline, solutions contain lower concentrations of H+ ions than pure water and have pH values above 7.
Section 2-3: Carbon Compounds
Four groups of carbon compounds found in living things are carbohydrates, lipids, nucleic acids, and protein.
Living things use carbohydrates as their main source of energy. Plants and some animals also use carbohydrates for structural purposes.
Lipids can be used to store energy. Some lipids are important parts of biological membranes and waterproof coverings.
Nucleic acids store and transmit hereditary, or genetic, information.
Some proteins control the rate of reactions and regulate cell processes. Some proteins build tissues such as bone and muscle. Others transport materials or help to fight disease.
Section 2-4: Chemical Reactions and Enzymes
Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products.
Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.
Cells use enzymes to speed up chemical reactions that take place in cells.