5.07 – Covalent Bonding


Ionic bonding is pretty straightforward.  Now we need to get into the intricacies of covalent bonding.  In this mission we will focus on the process of bonding, formal charge, and molecule shapes.  There is a lot to see here, so give yourself enough time to go through it and understand it all.

Lesson Objectives

  • Use atomic electron configurations and the octet rule to draw Lewis structures for molecules. (8.3)
  • Use electronegativity differences to identify nonpolar covalent, polar covalent, and ionic bonds. (8.4)
  • Calculate charge separation in diatomic molecules based on the experimentally measured dipole moment and bond length. (8.4)
  • Calculate formal charges from Lewis structures and use those formal charges to identify the dominant Lewis structure for a molecule or ion. (8.5)
  • Recognize molecules where resonance structures are needed to describe the bonding and draw the dominant resonance structures. (8.6)
  • Recognize exceptions to the octet rule and draw accurate Lewis structures even when the octet rule is not obeyed. (8.7)

To become familiar with the topics presented in this mission, view the slides below and take note of the key ideas.  These are from sections 8.3-8.7 of your text.

Now work through the practice problems, and post your work to OneNote.

Work out these mastery problems and check your answers in OneNote.  Post your work when finished, including any corrections.  These questions are from the 13th edition of the Brown Lemay text and a released AP Exam.

8.52 (13th)       For each of the following molecules or ions of sulfur and oxygen, write a single Lewis structure that obeys the octet rule, and calculate the oxidation numbers and formal charges on all the atoms:

(a) SO2

 

(b) SO3

 

(c) SO32–

 

(d) Arrange these molecules/ions in order of increasing S — O bond length.

 

 

8.64 (13th)       Draw the Lewis structures for each of the following molecules or ions. Identify instances where the octet rule is not obeyed; state which atom in each compound does not follow the octet rule; and state how many electrons surround these atoms:

 

 

(a) NO

 

(b) BF3
(c) ICl2

 

(d) OPBr3 (the P is the central atom)

 

(e) XeF4

2007 FRQ #6

This was a lot of information and we will need to spend a lot of time practicing and reviewing.  I recommend checking out the back of chapter 8 and working on more relevant problems.