Here are the solutions to the questions:
3. Draw the structural formula for each of the following compounds:
a) 2-methylheptane
Step 1: Draw a 7-carbon chain (heptane).
Step 2: Add a methyl group (CH3) to the second carbon.
Step 3: Fill in the remaining hydrogen atoms to satisfy carbon's valency of four.
HHH∣H−C−H∣−C−C−C−C−C−C−C−H∣∣∣∣∣∣∣HHHHHH
b) 3-ethylhexane
Step 1: Draw a 6-carbon chain (hexane).
Step 2: Add an ethyl group (CH2CH3) to the third carbon.
Step 3: Fill in the remaining hydrogen atoms.
HHHH∣∣H−C−C−H∣∣−C−C−C−C−C−C−H∣∣∣∣∣∣HHHHH
c) 2,2,4-trimethylpentane
Step 1: Draw a 5-carbon chain (pentane).
Step 2: Add two methyl groups to the second carbon and one methyl group to the fourth carbon.
Step 3: Fill in the remaining hydrogen atoms.
HHHH∣∣H−C−HH−C−H∣∣−C−C−C−C−C−H∣∣∣∣∣HHHH∣H−C−H∣H
d) 2,3-dichlorobutane
Step 1: Draw a 4-carbon chain (butane).
Step 2: Add a chlorine atom to the second carbon and another to the third carbon.
Step 3: Fill in the remaining hydrogen atoms.
HHH−C−C−C−C−H∣∣∣∣ClClH∣∣H
4. Draw and name the structures of all the isomers of:
a) Butane (C4H10)
• n-Butane (straight chain)
H−C−C−C−C−H∣∣∣∣HHHH∣∣∣∣HHHH
• 2-methylpropane (isobutane)
HHH∣H−C−H∣−C−C−C−H∣∣∣HH∣H
b) Pentane (C5H12)
• n-Pentane (straight chain)
H−C−C−C−C−C−H∣∣∣∣∣HHHHH∣∣∣∣∣HHHHH
• 2-methylbutane (isopentane)
HHH∣H−C−H∣−C−C−C−C−H∣∣∣∣HHH∣H
• 2,2-dimethylpropane (neopentane)
HHH∣H−C−H∣−C−C−C−H∣∣∣HH∣H−C−H∣H
c) Hexane (C6H14)
• n-Hexane (straight chain)
H−C−C−C−C−C−C−H∣∣∣∣∣∣HHHHHH∣∣∣∣∣∣HHHHHH
• 2-methylpentane
HHH∣H−C−H∣−C−C−C−C−C−H∣∣∣∣∣HHHH∣H
• 3-methylpentane
HHH∣H−C−H∣−C−C−C−C−C−H∣∣∣∣∣HHHH∣H
• 2,2-dimethylbutane
HHH∣H−C−H∣−C−C−C−C−H∣∣∣∣HHH∣H−C−H∣H
• 2,3-dimethylbutane
\begin{align*}
&\quad \quad \quad H \quad H \\
&\quad \quad \quad \mid \quad \mid \\
&\quad \quad H-C-H \quad H-C-H \\
&\quad \quad \quad \mid \quad \mid \\
H &-C-C-C-C-H \\
&\mid \quad \mid \
