Year 8 Science · Unit 2 · Lesson 05

Matter, Bringing It Together

Challenge Worksheet

Name

Date

Class

Learning Goals

Evaluate scientific claims and models using criteria from Lessons 1–4.
Interpret chemical formulas to determine bonding and classification in a real-world context.
Predict and justify what happens to matter when conditions change, using particle-level reasoning.

Go Deeper

What if…?

Scenario

A food scientist at a Sydney flavour laboratory is developing a new seasoning blend. She combines three ingredients: NaCl (sodium chloride, common table salt), C₁₂H₂₂O₁₁ (sucrose, a sugar), and a small amount of synthetic vanillin (C₈H₈O₃), a flavour compound. She stirs the three ingredients together thoroughly. No chemical reaction occurs during the mixing, each ingredient keeps its own chemical identity. The scientist then places the blend in an oven set to 200 °C.

Using ideas from this unit, answer all three parts in your response below:

(a) Classify the final blend before heating. Is it an element, compound or mixture? Justify your answer using particle-level reasoning.
(b) For each of the three ingredients, explain what its chemical formula tells you about the type and ratio of atoms present, and whether each ingredient is an element or a compound.
(c) Predict what would happen to the blend when heated to 200 °C. Consider that sucrose melts around 186 °C and begins to decompose. Use ideas about particles, bonds and classification to support your prediction.

Challenge 6 marks

Show What You Know

1. In Lesson 4 you learned that a particle diagram is a scientific model. Using the criteria for a "good model" from that lesson, such as accuracy, simplicity, and usefulness, evaluate whether a particle diagram is a good model of matter. In your answer, identify at least one strength and one limitation.

Challenge 4 marks

2. Consider these five everyday substances: table salt, water, air, copper wire, and granite. A scientist claims: "All five substances can be fully described using only two of the four tools, classification and particle diagrams, so symbols and models are unnecessary." Do you agree or disagree? Justify your position using at least two of the five substances as evidence.

Challenge 4 marks

Wrap Up

In one sentence, explain why scientists use multiple tools together rather than just one when describing matter.