Year 9 Science · Unit 2 · Lesson 05

Organic and Inorganic Compounds

Foundation Worksheet

Name

Date

Class

Learning Goals

Define organic and inorganic compounds using the C–H bond rule.
Classify common substances as organic or inorganic from their chemical formulas.
Explain why carbon can form millions of different compounds.

Warm Up

Match each term to its definition

Write the letter of the matching definition in the middle column. Each letter is used once.

Term	Letter	Definition
Organic compound		A. A compound made of only carbon and hydrogen atoms, such as methane, CH₄.
Inorganic compound		B. The chain or ring of carbon atoms that forms the structure of an organic molecule.
Carbon		C. A compound that contains carbon atoms bonded to hydrogen atoms (C–H bonds).
Hydrocarbon		D. A group of atoms, such as –OH, that gives an organic molecule its typical properties.
Functional group		E. The element with four outer (valence) electrons, so it can form four bonds.
Carbon backbone		F. A compound with no C–H bonds, such as salts, most minerals and carbon dioxide.

1. State the rule chemists use to decide whether a compound is organic. Why is carbon dioxide, CO₂, classified as inorganic even though it contains carbon?

Recall 2 marks

Your Turn

Sort it

Write each compound in the correct box. Use the chemical formula to decide.

Methane CH₄ Water H₂O Ethanol C₂H₅OH Table salt NaCl Glucose C₆H₁₂O₆ Iron oxide Fe₂O₃ Carbon dioxide CO₂ Polyethylene (CH₂)ₙ Calcium carbonate CaCO₃ Aspirin C₉H₈O₄

Organic compounds (contain C–H bonds)

Inorganic compounds (no C–H bonds)

Go Deeper

Demonstration: does it burn?

In a fume cupboard, a teacher held a small sample of each substance in a flame.

Table 1. Flame test results

Substance	Formula	Burned?
Table sugar	C₁₂H₂₂O₁₁	Yes, it charred
Washing soda	Na₂CO₃	No
Candle wax	C₂₅H₅₂	Yes
Sand	SiO₂	No
Citric acid	C₆H₈O₇	Yes, it charred

Source: teacher demonstration. C₂₅H₅₂ is a typical molecule in candle wax.

2. Complete the last column of Table 1. Then explain your decision for washing soda.

Apply 2 marks

3. Describe the pattern in Table 1 that links organic compounds and burning. Use it to predict whether table salt, NaCl, would burn.

Analyse 2 marks

Show What You Know

4. Carbon is only one element, yet there are more than 10 million known organic compounds. Explain how this is possible.

Apply 4 marks

Exit ticket

Your kitchen has sugar, salt and vinegar. Which of them contain organic compounds? Give a reason.