Download Exercise 8: Covalent bonds

Chemistry 161
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Exercise 8: Covalent bonds and Lewis structures
Lewis (electron) dot structures
Draw the Lewis dot structures for the following molecules and ions. Give a total
valence electron count as well. For the molecules or ions that have atoms that do
not follow the octet rule, explain how they can break the octet rule. For ions, use
the square bracket and charge notation (see top of p. 387 for an example).
1. H2CO
2. NOBr
3. NO2+ (nitrite cation)
4. NO2– (nitrite anion)
5. POCl3
6. SF6
7. Which of the six structures you’ve drawn require the indication of formal
charge? Then write the formal charge(s) next to the appropriate atom(s),
following the example on page 390.
Organic molecules, functional groups and polarity
8. The structure for serine is shown below. Mark and label three functional
groups, as defined in Chapter 9, on this molecule. Hint: serine is an amino acid.
9. Circle the chemical bonds on
serine that are considered polar.
The book is vague about this
point, so use the criterion that if
the electronegativity difference
between the two atoms joined by
the bond is 0.5 or greater, then
that bond is polar. Note that
some bonds have been
abbreviated.