Year 9 Science · Unit 2 · Lesson 13
Foundation Worksheet
Learning Goals
Match each term to its meaning
Write the letter of the correct meaning next to each term. Each letter is used once.
| Term | Letter | Meaning |
|---|---|---|
| condensed formula | A. shows every atom and every bond | |
| -ane | B. groups the atoms without drawing the bonds, e.g. CH₃CH₂CH₃ | |
| displayed formula | C. the chain has six carbon atoms | |
| hex- | D. shows only the number of each type of atom, e.g. C₃H₈ | |
| prop- | E. the molecule is an alkane, with only single bonds | |
| molecular formula | F. the chain has three carbon atoms |
1. The molecular formula C₅H₁₂ belongs to a straight-chain alkane. State its IUPAC name and write its condensed formula.
2. Draw the displayed formula of propane, C₃H₈. Check that every carbon atom has four bonds.
Odd one out
In each group, one item does not belong. Write the odd one out and your reason.
| # | Group | Odd one out and reason |
|---|---|---|
| 1 | methane · ethanol · propane · butane | |
| 2 | C₄H₁₀ · CH₃CH₂CH₂CH₃ · CH₃CH₂CH₃ · butane | |
| 3 | benz- · meth- · prop- · hex- |
Read the data
| Formula | Carbon atoms | Hydrogen atoms |
|---|---|---|
| CH₄ | 1 | 4 |
| C₂H₆ | 2 | 6 |
| C₃H₈ | 3 | 8 |
| C₄H₁₀ | 4 | 10 |
| C₅H₁₂ | 5 | 12 |
| C₆H₁₄ | 6 | 14 |
3. Plot the number of hydrogen atoms (vertical axis) against the number of carbon atoms (horizontal axis). Draw a straight line through the points.
4. Extend your line to 8 carbons and read off the value it predicts. Then name the compound and give its formula.
5. Every step along your line adds 1 carbon atom and 2 hydrogen atoms. Which unit is added each time, and what is the name for a family of compounds that grows like this?
Scenario: checking bottle labels
A lab technician is checking four new labels before they go on bottles. Some labels are wrong.
| Bottle | Name on label | Formula on label |
|---|---|---|
| 1 | ethane | CH₃CH₃ |
| 2 | butane | C₄H₈ |
| 3 | hexane | CH₃CH₂CH₂CH₂CH₃ |
| 4 | propane | C₃H₈ |
6. Which two labels are wrong? For each, explain the mistake and write the correct formula for the name on the label.
7. A chemist in Sydney orders “hexane, CH₃CH₂CH₂CH₂CH₂CH₃” from a supplier in Japan. Explain how the IUPAC name and the condensed formula each help the supplier send exactly the right substance, and what a displayed formula would show that the molecular formula C₆H₁₄ does not.