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Principles of Biology - Biology 101
Fall Qtr
Lake Tahoe Community College
Instructor: Sue Kloss
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Chapter 2 – Context for the Chemistry of Life
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I.
Matter
A. elements and compounds
1. element
2. compound
B. essential elements of life
1. macronutrients
2. trace elements
II.
Element’s properties
A. Atoms
B. Subatomic particles
1. proton
a. dalton
2. neutron
3. electron
4. nucleus
C. Atomic number and atomic mass
1. atomic number
2. atomic mass
D. Isotopes
1. carbon 12
2. 13C , 14C
3. 14C is unstable when decay leads to change in proton number, it changes element.
4. 14C decays to N.
a. radioactive isotopes
E. Energy levels of electrons
1. nuclei don’t interact
2. only electrons interact in chemical reactions
3. Energy
4. potential energy
5. energy levels
a. electron shells
b. relationship of shells to potential energy
c. electron absorbs and lose energy
III. Electron configuration and chemical behavior
A. Periodic table of the elements
1. first three periods - organic molecules
2. periods - electron shells
a. first shell
b. shells other than the first
c. chemical behavior of an atom
d. valence electrons, valence shell
e. nonreactive atoms, also called inert
g. incomplete valence shells
B. Electron orbitals
1. s orbital
2. p orbitals
IV. Molecular structure and function and chemical bonding
A. Covalent bonds
1. molecule
a. single covalent bond
b. double covalent bond
2. molecular formula
3. valence
4. electronegativity
5. nonpolar covalent bond
6. polar covalent bond
B. Ionic bonds
1. electrons stripped away from the partner by the more electronegative
a. cation
b. anion
c. ionic compounds
1. salts
2. the formula for ionic compounds
f. the term ion also applies to molecules that are electrically charged
C. Weak Chemical Bonds
1. ionic bonds are considered weak bonds
2. Hydrogen bonds are weak bonds also- hugely important in chemistry of life
3. Van der waals interactions
4. 3D shape in molecules
D. Molecular shape and function
1. characteristic shapes, very important to function
2. shape is critical- determines how 2 molecules will interact with one another
V. Chemical reactions make and break chemical bonds
A. making and breaking of chemical bonds
1. 1st law of thermodynamics – all matter must be accounted for
a. 2 H2 + O2 ----- 2 H2O
b. 6 CO2 + 6 H2O -- ?C6H12O6 + ?O2
2. reactants = H2 (how many?) + O2
3. products = C6H12O6 + O2
4. -- indicates reaction proceeds
5. arrows in both directions indicates reaction is reversible
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Chapter 2 – Lesson Objectives
Distinguish between an element and a compound.
Identify the four elements that make up 96% of living matter.
Define the term trace element and give an example.
Draw and label a simplified model of an atom. Explain how this model simplifies our understanding of atomic
structure.
Distinguish between each of the following pairs of terms:
a. neutron and proton
b. atomic number and mass number
c. atomic weight and mass number
Explain how the atomic number and mass number of an atom can be used to determine the number of neutrons.
Explain how two isotopes of an element are similar. Explain how they are different.
Describe two biological applications that use radioactive isotopes. Explain how one of these applications works.
Define the terms energy and potential energy. Explain why electrons in the first electron shell have less potential
energy than electrons in higher electron shells.
Distinguish among nonpolar covalent, polar covalent and ionic bonds.
Explain why strong covalent bonds and weak bonds are both essential in living organisms.
Distinguish between hydrogen bonds and van der Waals interactions.
Give an example that illustrates how a molecule’s shape can determine its biological function.
Explain what is meant by a chemical equilibrium.