Question 1
Is CH₃CH₂OH a structural isomer of CH₃OH? Explain.
Need a hint for Question 1?
First compare molecular formulae. Only then compare the arrangement.
Check Question 1
No. Their molecular formulae differ: C₂H₆O and CH₄O.
STUDENT SPACE · TOPIC 2
Names and structural isomers
Name unbranched compounds and distinguish positional and chain isomers.
The essentials
- Meth-, eth-, prop- and but- indicate 1, 2, 3 and 4 carbon atoms. Endings identify the family.
- CH₂=CHCH₂CH₃ is but-1-ene. CH₃CH=CHCH₃ is but-2-ene. Number from the end nearest the double bond.
- Structural isomers have the same molecular formula and different structural formulae.
- A saturated compound has only single carbon–carbon bonds. Unsaturated compounds contain a carbon–carbon multiple bond.
Key vocabulary
| English | Chinese |
|---|---|
| structural isomer | 结构异构体 |
| saturated | 饱和的 |
| unsaturated | 不饱和的 |
Quick practice
Try each question before opening its hint or answer. Use paper for calculations and diagrams.
Question 2
Draw displayed formulae for butan-1-ol and butan-2-ol.
Need a hint for Question 2?
Move the –OH group without changing the four-carbon chain.
Check Question 2
Butan-1-ol: CH₃CH₂CH₂CH₂OH. Butan-2-ol: CH₃CH(OH)CH₂CH₃. Show every atom and bond.
Question 3
Name CH₃CH₂COOH. State its total number of carbon atoms.
Need a hint for Question 3?
Count the carbon within –COOH as part of the chain.
Check Question 3
Propanoic acid, three carbon atoms including the carbon in COOH.
Use Lesson 2 in your worksheet for written practice. Your teacher will discuss those answers in class.