2.1 The Nature of Matter

The subatomic particles that make up atoms are protons, neutrons, and electrons.

All isotopes of an element have the same chemical properties, because they have the same number of electrons.

The physical and chemical properties of a compound are usually very different from those of the elements from which it is formed.

The main types of chemical bonds are ionic bonds and covalent bonds.

• atom (34)

• ionic bond (37)

• nucleus (34)

• ion (37)

• electron (34)

• covalent bond (37)

• element (35)

• molecule (37)

• isotope (35)

• van der Waals forces (38)

• compound (36)

2.2 Properties of Water

Water is a polar molecule. Therefore, it is able to form multiple hydrogen bonds, which account for many of its special properties.

Water's polarity gives it the ability to dissolve both ionic compounds and other polar molecules.

Buffers play an important role in maintaining homeostasis in organisms.

• hydrogen bond (41)

• solution (42)

• pH scale (43)

• cohesion (41)

• solute (42)

• acid (44)

• adhesion (41)

• solvent (42)

• base (44)

• mixture (42)

• suspension (42)

• buffer (44)

2.3 Carbon Compounds

Carbon can bond with many elements, including hydrogen, oxygen, phosphorus, sulfur, and nitrogen to form the molecules of life.

Living things use carbohydrates as their main source of energy. Plants, some animals, and other organisms 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.

• monomer (46)

• nucleic acid (48)

• polymer (46)

• nucleotide (48)

• carbohydrate (46)

• protein (48)

• monosaccharide (46)

• amino acid (48)

• lipid (47)

2.4 Chemical Reactions and Enzymes

Chemical reactions always involve changes in the chemical bonds that join atoms in compounds.

Chemical reactions that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a source of energy.

Enzymes speed up chemical reactions that take place in cells.

Temperature, pH, and regulatory molecules can affect the activity of enzymes.

• chemical reaction (50)

• catalyst (52)

• reactant (50)

• enzyme (52)

• product (50)

• substrate (52)

• activation energy (51)

Think Visually Create a table in which you compare the structures and functions of the following macromolecules: carbohydrates, lipids, proteins, and nucleic acids.