General Chemistry Principles, Patterns, and Applications, 2011

1. In each reaction, identify the Lewis acid and the Lewis base and complete the reaction by writing the
products(s).
a. (CH 3 ) 2 O + AlCl 3
b. SnCl 4 + 2 Cl −
2. Use Lewis dot symbols to depict the reaction of BCl 3 with dimethyl ether [(CH 3 ) 2 O]. How is this reaction
similar to that in which a proton is added to ammonia?
A N S W E R
1.
a. AlCl 3 is the Lewis acid, and the ether is the Lewis base; AlCl 3 + (CH 3 ) 2 O → AlCl 3·O(CH 3 ) 2
b. SnCl 4 is the Lewis acid, and chloride is the Lewis base; SnCl 4 + 2 Cl − → SnCl 6
2−
8.8 Properties of Covalent Bonds
L E A R N I N G O B JE C T I V E
1. To understand the relationship between bond order, bond length, and bond energy.
In proposing his theory that octets can be completed by two atoms sharing electron pairs, Lewis provided scientists
with the first description of covalent bonding. In this section, we expand on this and describe some of the properties
of covalent bonds.
Bond Order
When we draw Lewis structures, we place one, two, or three pairs of electrons between adjacent atoms. In
the Lewis bonding model, the number of electron pairs that hold two atoms together is called
the bond order. For a single bond, such as the C–C bond in H3C–CH3, the bond order is one. For a double
bond (such as H2C=CH2), the bond order is two. For a triple bond, such as HC≡CH, the bond order is
three.
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