Chem 250
Chapter 9 Study Guide
Covalent Bonding
9.1 The Covalent Bond
• Apply the octet rule to atoms that bond covalently.
• Describe the formation of single, double, and triple covalent bonds.
• Relate the strength of covalent bonds to bond length and bond dissociation energy.
9.2 Naming Molecules
• Identify the names of binary molecular compounds from their formulas.
• Name acidic solutions.
9.3 Molecular Structures
• List basic steps used in drawing Lewis structures.
• Explain why resonance occurs, and identify resonance structures.
• Explain three exceptions to the octet rule (expanded octet, less than 8 e-s, odd # of e-s), and identify molecules in which these
exceptions occur.
9.4 Molecular Shape
• Discuss the VSEPR bonding theory.
• Predict the shape of and the relative bond angles in a molecule.
9.5 Electronegativity and Polarity
• Describe how electronegativity is used to determine bond type.
• Compare and contrast polar and nonpolar covalent bonds and polar and nonpolar molecules.
• Describe the characteristics of compounds that are covalently bonded, and contrast these characteristics to those of substances
that have ionic bonds and metallic bonds.
You are NOT responsible for sigma and pi bonds (pg. 245-246) and hybrid orbitals (“Hybridization” in section 9.4, pg. 261).
WebAssign due by Sunday, Nov. 10, 11:00 pm
Monday
In Class:
Homework:
10-28-13
Chapter 8 test.
Read 9.1.
Tuesday
In Class:
Homework:
10-29-13
Half-Day Schedule -- Parent-Teacher Conferences
Introduction to covalent bonding. Lewis Dot Structures, single, double, and triple covalent bonds.
Read 9.3 and 9.4, answer questions #1-5 on pg. 244 (answers should go in your binder, check your answers in the back
of the book.) Read Rules for Drawing Lewis Structures (on the back of the study guide).
Wednesday
10-30-13
Thursday
In Class:
10-31-13
Happy Halloween!
Determining Lewis Dot Structural formulas. Exceptions to the octet rule (expanded octet).
VSEPR model
and molecular shapes.
Problems #30-38 on pp. 255-256 (write your answers in your binder, then check answers with solutions in the back
of the book.) WebAssign.
Homework:
Friday
In Class:
Homework:
No School – Faculty In-Service
11-1-13
Mass Schedule – All Saints’ Day
VSEPR model and molecular shapes. More exceptions to the octet rule (odd # e-s, less than 8 e-s) Resonance
structures.
Read Lab 14 – Model Building (you will not need goggles). This is not the lab in your lab manual. I will post it in the
shared Google folder. Do all of the Lewis Dot Structures before coming to class. Have the lab pages printed and
stapled before you come to class Wednesday. WebAssign.
Monday
11-4-13
No School – Faculty Retreat
Tuesday
11-5-13
No School – Archbishop’s Day Off
Wednesday
In Class:
Homework:
11-6-13
Lab 14 – Model Building (you will not need goggles). You will turn in the lab before the end of class.
Read 9.2 and 9.5. WebAssign. Read and begin learning the handout on naming molecular compounds
(nomenclature). Page 262, problems 49-53 (write your answers in your binder, then check answers in the back of the
book.)
Cont. on back side…
Thursday
In Class:
Homework:
11-7-13
Naming molecular compounds. Electronegativity and nonpolar bonds / polar covalent bonds / ionic bonds.
Problems #13-22 on pp. 249-250, problems #60-63 on pg. 266 (answers should go in your binder, then check answers
with solutions in the back of the book.) WebAssign.
Friday
In Class:
Homework:
11-8-13
Father / Son Mass – 7:20 am
Polar/nonpolar molecules, properties of molecular compounds.
WebAssign due Sunday at 11:00 pm. Review for Chapter 9 test.
Monday
In Class:
Homework:
11-11-13
Chapter 9 Test.
TBA
Rules for Drawing Lewis Structures
The following is a step-by-step guide to drawing Lewis structures for simple molecules.
1. Count the total number of valence electrons for all atoms in the compound.
If you are finding the structure of an ion, remember to add electrons for a negative charge and subtract electrons
for a positive charge.
2. Divide the total number of valence electrons by two to get the number of electron pairs in the molecule (each
pair of electrons will be a covalent bond between two atoms or it will be an unshared pair on an atom.)
3. Predict the arrangement of the atoms in the molecule, drawing a line to represent a single bond (one electron
pair) between each pair of bonded atoms.
a. The first atom listed in the formula, or the atom with the least attraction for shared electrons, is
usually the central atom.
b. Remember that H can only be bonded to one other atom
4. Determine the number of electron pairs left over after drawing the single bonds (electron pairs).
5. Place the remaining electron pairs around the outside atoms (not the central atom) until each outer atom is
surrounded by eight electrons. (The octet rule.)
Remember that H will only have two electrons.
6. Place any left over electron pairs around the central atom.
a. It is ok to have more than eight electrons (one exception to the octet rule) around the central atom as long as
it is from at least the third period on the periodic table.
7. If there are not enough electrons to put eight around the central atom, go back and try moving unshared
electron pairs to become shared electron pairs between atoms. This creates double or triple bonds. Double or
triple bonds are most commonly formed between C, N, O, and S.