Year 7 Science · Unit 2 · Lesson 6

Metals, Non-metals and Metalloids

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Learning Goals

Apply a systematic classification process using the periodic table and physical properties.
Trace a cause-and-effect chain from silicon's semiconductor properties to modern technology.
Justify classifications using multiple lines of evidence.

Warm Up

Order the steps

Number the steps from 1 to 7 to show the correct order for classifying an unknown element as metal, non-metal or metalloid using the periodic table and property testing. Step 1 = what you do first.

Order	Step
	Test the element for conductivity using a simple circuit — does electricity flow through?
	Check whether the element sits on the staircase line itself — if so, classify it as a metalloid.
	Obtain a sample of the unknown element and record any obvious physical observations (colour, lustre, state at room temperature).
	Find the element on the periodic table and note whether it sits to the left or right of the staircase line.
	Test if the element is malleable by trying to flatten it — metals bend, non-metals shatter.
	Combine all evidence (position on table + physical properties tested) to make a final classification.
	Look up or identify the element's symbol from the periodic table tile.

Your Turn

Because… chain

Fill in the missing effects. Each cause leads to the next step in the chain, ending with smartphones. The first box in each row is given.

Silicon (Si) is a metalloid with "switchable" conductivity — it conducts electricity only sometimes

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Silicon can be "doped" with tiny amounts of other elements to control exactly when it conducts

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Transistors (tiny electrical switches made from silicon) can be switched on and off millions of times per second

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Billions of transistors are packed onto a fingernail-sized silicon chip

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Overall outcome — why silicon's metalloid nature matters:

Show What You Know

1. Aluminium (Al) is mined from bauxite ore in Cape York, Queensland. List two properties of aluminium that make it useful as a structural metal (e.g. for aircraft and vehicle bodies). Explain why each property is useful for that purpose.

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2. A student claims: "Graphite (a form of carbon) is a metal because it conducts electricity." Using what you know about how to classify elements, explain why this reasoning is flawed and give the correct classification for carbon.

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Wrap Up

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