General Chemistry Principles, Patterns, and Applications, 2011

7. The B–N bond is significantly more polar than the C–C bond, which makes B–N compounds more reactive and
generally less stable than the corresponding carbon compounds. Increased polarity results in less
delocalization and makes the planar form of BN less conductive than graphite.
8.
9. Partial pi bonding between O and B increases the B–O bond strength.
10.
11. Periodic trends predict that the cations of the heavier elements should be easier to reduce, so the elements
should have less negative reduction potentials. In fact, the reverse is observed because the heavier elements
have anomalously high Z eff values due to poor shielding by filled (n − 1)d and (n − 2)f subshells.
12.
13. dsp 3 S T R U C T U R E A N D R E A C T I V I T Y
1. Is B(OH) 3 a strong or a weak acid? Using bonding arguments, explain why.
2. Using bonding arguments, explain why organoaluminum compounds are expected to be potent Lewis acids
that react rapidly with weak Lewis bases.
3. Imagine that you are studying chemistry prior to the discovery of gallium, element 31. Considering its
position in the periodic table, predict the following properties of gallium:
a. chemical formulas of its most common oxide, most common chloride, and most common
hydride
b. solubility of its oxide in water and the acidity or basicity of the resulting solution
c. the principal ion formed in aqueous solution
4. The halides of Al, Ga, In, and Tl dissolve in water to form acidic solutions containing the hydrated metal ions,
but only the halides of aluminum and gallium dissolve in aqueous base to form soluble metal-hydroxide
complexes. Show the formulas of the soluble metal–hydroxide complexes and of the hydrated metal ions.
Explain the difference in their reactivities.
5. Complete and balance each chemical equation.
a. a. BCl 3
g
( ) + H 2 ( g) - ® D
b. 6C 2 H 4 (g) + B 2 H 6 (g) →
c. B 2 H 6 (g) + 3Cl 2 (g) →
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