Year 8 Science · Unit 2 · Lesson 15
Challenge Worksheet
Learning Goals
What if…?
Scenario
Copper is now ten times more expensive than aluminium, making copper wire unaffordable for most household electrical wiring in Australia. An engineer proposes switching all standard household wiring from copper to aluminium. She argues that aluminium is a metal in the same broad category as copper, so it should work just as well.
Copper sits in Period 4, Group 11 (atomic number 29). Aluminium sits in Period 3, Group 13 (atomic number 13). Both are metals that conduct electricity. However, their positions in the periodic table reveal important differences in their properties.
Using what you know about periodic table position, element category and physical properties, evaluate the engineer's proposal. In your answer: (i) identify which properties of aluminium make it a plausible substitute for copper wiring, and (ii) identify at least two properties or safety concerns, linked to their periodic table position or category, that would need to be addressed before the switch could be safely made.
1. A scientist claims: "Because copper and aluminium are both metals on the periodic table, they must have identical electrical properties and can always be swapped for each other in any application." Evaluate this claim. Identify what is correct, what is wrong, and use periodic table evidence to explain the difference.
2. Silicon (Si) is a metalloid in Period 3, Group 14. Explain why silicon, rather than a pure metal or a pure non-metal, is used in computer chips. In your answer, use the concept of category (metal / non-metal / metalloid) and the idea of choosing features from the periodic table that actually help answer the question.
Wrap Up
In one sentence, what was the main idea of this lesson?