Year 8 Science · Unit 2 · Lesson 15
Apply Worksheet
Learning Goals
Order the steps
Number the steps from 1 to 6 to show the correct order for using the periodic table to choose the right element for an electrical wire. Step 1 = what you do first.
| Order | Step |
|---|---|
| Eliminate metals that are too reactive, Group 1 metals (sodium, potassium) react dangerously with water and air | |
| Choose copper for household wiring (better conductor) or aluminium for long-distance power lines (cheaper and lighter) | |
| Narrow the search to metals, metals sit on the left and centre of the periodic table and conduct electricity | |
| Identify what properties the wire needs: conducts electricity well, can be drawn into a thin wire (ductile), and is affordable | |
| Eliminate very heavy or extremely expensive metals, platinum and gold conduct well but are not practical at scale | |
| Compare copper (Period 4, Group 11) and aluminium (Period 3, Group 13), both ductile metals with good conductivity |
Scenario
An engineer is choosing a gas to fill balloons for a children's party at a primary school. She has access to helium (Group 18, Period 1) and hydrogen (Group 1, Period 1). Both gases are lighter than air, so both would make a balloon float. However, the two elements sit in very different groups of the periodic table, which affects their properties significantly.
(a) Predict which gas the engineer should choose for a public children's event. Write your prediction as a clear recommendation.
(b) Justify your choice by comparing the group properties of helium and hydrogen. Do not simply refer to historical disasters, use what the group position of each element tells you about its reactivity and behaviour.
1. Chlorine is added to Sydney's drinking water supply to kill harmful microorganisms. Using the periodic table, explain what group chlorine belongs to and why this group position makes it suitable for this purpose.
2. Aluminium (Period 3, Group 13) is used to build aircraft frames instead of iron (Period 4, Group 8). Use both period number and category to explain why aluminium is preferred for aerospace applications.
Wrap Up
In one sentence, what was the main idea of this lesson?