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 the chemistry definition of "organic" differs from everyday use of the word.

Warm Up

Match each term to its definition

Draw a line connecting each term on the left to its correct definition on the right. Or write the matching letter next to each term.

Term	Your answer	Definition
Organic compound		A. The branch of chemistry that studies carbon-containing compounds with C–H bonds.
Inorganic compound		B. A compound that contains a carbon–hydrogen (C–H) backbone, originally associated with living things but now includes synthetic carbon compounds.
Carbon		C. A food labelling term meaning grown without synthetic pesticides or fertilisers, has nothing to do with whether the food contains C–H bonds.
Hydrocarbon		D. An organic compound that contains only carbon and hydrogen atoms, with no other elements present (e.g. methane, CH₄).
Organic food (everyday use)		E. A compound that does not contain carbon–hydrogen bonds, includes salts, metals, minerals, and most gases.
Organic chemistry (chemistry definition)		F. The element with four valence electrons that forms the backbone of all organic molecules, capable of bonding in chains, branches, and rings.

Note: "Organic food" (everyday use) and "organic compound" (chemistry) use the same word but mean very different things. In chemistry, water H₂O is inorganic and polyethylene plastic is organic!

Your Turn

Sort it!

Write each compound from the pool into the correct category box. Use the chemical formula to help you decide: look for C–H bonds.

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)

Hint: CO₂ contains carbon but has no C–H bonds, it is classified as inorganic. Carbonates (CaCO₃) are also treated as inorganic.

Show What You Know

1. State the rule chemists use to decide whether a compound is organic or inorganic. Why is carbon dioxide (CO₂) considered inorganic even though it contains the element carbon?

Recall 2 marks

2. A supermarket sells "organic" carrots for a higher price. A student says, "Organic carrots must have more organic compounds than regular carrots." Explain why this statement is scientifically incorrect, using the chemistry definition of organic.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?