http://www.ck12.org Chapter 9. Covalent Bonding
- Exceptions to the octet rule include incomplete octets, odd-electron molecules, and expanded octets.
- Bond energy is the energy required to break a covalent bond. The most stable and unreactive molecules contain
bonds with high bond energies.
Lesson Review Questions
Reviewing Concepts
- Identify the compounds below as being most likely ionic or molecular.
a. CaBr 2
b. PCl 3
c. H 2 S
d. ZnO - Describe the difference between ionic and covalent bonds.
- Describe the attractive and repulsive forces that occur as two atoms approach one another and form a covalent
bond. - How many electrons are shared between atoms in a single covalent bond? In a double covalent bond? In a
triple covalent bond? - How does the bond length between the oxygen atoms in an ozone molecule compare to the bond lengths of
oxygen-oxygen single and double bonds? Explain. - Which elements are capable of exceeding the octet rule when forming covalent bonds. Why?
Problems
- Draw Lewis structures for the following molecules, each of which follows the octet rule.
a. H 2 S
b. PCl 3
c. HCN
d. H 2 CO
e. OF 2
f. BrCl
g. CS 2
h. C 2 H 6 - Draw Lewis structures for the following polyatomic ions.
a. SO 32 −
b. OH−
c. PO 43 − - Draw all resonance structures for the carbonate ion, CO 32 −.
- Compounds that contain a C–N and/or a C–O bond are capable of forming a coordinate covalent bond with
the H+ion. Compounds that only contain C–C and C–H bonds cannot. Explain this observation. - Draw Lewis structures for the following molecules. Which do not follow the octet rule?
a. AlH 3
b. SF 4
c. BeCl 2
d. SCl 2
e. NO