The Chemical Basis of Life
Chapter 2 Objectives
Opening Essay
Explain how lemon ants prevent the growth of plants that could compete with lemonant
trees.
Elements, Atoms, and Molecules
2.1
2.2
2.3
2.4
2.4
2.4
2.5
2.6
2.7–2.10
Define matter, an element, and a trace element.
Explain how and why iodine, fluoride, and iron are added to the human diet.
Define a compound and explain how compounds in living organisms are different from
compounds in nonbiological materials.
Describe the structure of an atom.
Define the atomic number and mass number of an atom.
Define an isotope and explain what makes some isotopes radioactive.
Describe the dangers and uses of radioactive isotopes.
Explain how the electron configuration of an atom influences its chemical behavior.
Distinguish between ionic bonds, nonpolar covalent bonds, polar covalent bonds, and
hydrogen bonds, noting their relative strengths and how and where they form.
Water’s Life-Supporting Properties
2.11–2.14
2.11
2.12
2.14
2.15
2.15
2.15
2.16
2.17
Describe the special properties of water that make it vital to living systems. Explain how
these properties are related to hydrogen bonding.
Define and distinguish between cohesion and surface tension.
Define and distinguish between heat and temperature.
Define a solute, a solvent, and a solution.
Explain how acids and bases directly or indirectly affect the hydrogen ion concentration
of a solution.
Explain the basis of the pH scale.
Explain how buffers function.
Describe the causes and consequences of acid precipitation and ocean acidification.
Explain why the search for extraterrestrial life centers on the search for water.
Chemical Reactions
2.18
Explain the significance of chemical reactions. Identify the reactants and products of
photosynthesis.
Key Terms
acid
acid precipitation
adhesion
aqueous solution
atom
atomic mass
atomic number
base
buffer
chemical bond
chemical reaction
cohesion
compound
covalent bond
double bond
electron
electron shell
electronegativity
element
heat
hydrogen bond
ion
ionic bond
isotope
mass number
matter
molecule
neutron
nonpolar covalent bond
nucleus (plural, nuclei)
pH scale
polar covalent bond
polar molecule
product
proton
radioactive isotope
reactant
salt
solute
solution
solvent
surface tension
temperature
trace element
Word Roots
an- 5 not (anion: a negatively charged ion)
aqua- 5 water (aqueous solution: a solution in which water is the solvent)
co- 5 together; -valent 5 strength (covalent bond: an attraction between atoms that share one or more
pairs of outer-shell electrons)
electro- 5 electricity (electronegativity: the attraction of a given atom for the electrons of a covalent
bond)
iso- 5 equal (isotope: a variant form of an atomic element having the same number of protons and
electrons but a different number of neutrons)
neutr- 5 neither (neutron: a subatomic particle no electrical charge)
pro- 5 before (proton: a subatomic particle with a single positive electrical charge)
Student Media
Elements, Atoms, and Molecules
Activity: Structure of the Atomic Nucleus (2.4)
Activity: Electron Arrangement (2.6)
Activity: Build an Atom (2.6)
Activity: Ionic Bonds (2.7)
Activity: Covalent Bonds (2.8)
Activity: Nonpolar and Polar Molecules (2.9)
Activity: Water’s Polarity and Hydrogen Bonding (2.10)
Process of Science: How Are Space Rocks Analyzed for Signs of Life? (2.1)
BLAST Animation: Covalent Bonds (2.8)
Water’s Life-Supporting Properties
MP3 Tutor: The Properties of Water (2.11)
Activity: Cohesion of Water (2.11)
Activity: Acids, Bases, and pH (2.15)
Process of Science: How Does Acid Precipitation Affect Trees? (2.16)
Discovery Channel Video Clip: Early Life (2.17)
BLAST Animation: Hydrogen Bonds in Water (2.11)
Chemical Reactions