Science 7–10 · Year 8

Metal or non-metal: testing lustre, conductivity and malleability

Periodic table and atomic structure

PracticalLow risk

The idea

Elements can be sorted as metals or non-metals by testing physical properties, and a few elements such as graphite and silicon break the pattern, which is why the classification rests on several properties rather than one.

Safety card

Low riskAn adult supervises

Hazards

sulfur dust is an eye irritant and flammable
flying fragments when brittle samples are struck
sharp foil and wire edges

Controls

eye protection throughout; samples always bent or struck inside a sealed bag
sulfur issued as a lump and returned to the teacher; no flames on the bench
wash hands after handling the samples

Note

NSW Department of Education, Chemical Safety in Schools (CSIS) 2021 Technical Update: Section 1.7 (risk assessment before use) and Volume 2 Appendix D (generic assessment advice, user codes and DoE categories). Complete a RiskAssess or CSIS site-specific risk assessment before the lesson. CSIS Appendix F lists sulfur under chemicals to be used with caution (flammable; forms sulfur dioxide when it burns).

What you need

labelled element samples about 3 cm long: copper wire, a strip of zinc foil, magnesium ribbon, iron wire, a strip of aluminium foil, graphite rod (or pencil lead), a lump of sulfur (issued by the teacher), a small piece of silicon (optional)
conductivity tester: 3 V battery pack, LED or 2.5 V torch bulb and two leads with crocodile clips
emery paper, pliers, small hammer, steel plate or old tile, zip-seal bags, hand lens

How to do it

Rub a small area of each sample with emery paper and record whether the fresh surface is shiny or dull.
Clip each sample between the leads of the tester and record whether the LED or bulb lights.
Inside a zip-seal bag, try to bend each sample once through a right angle with fingers or pliers; tap the sulfur, the graphite and the silicon gently with the hammer on the steel plate. Record whether the sample bends without breaking (malleable) or snaps or crumbles (brittle).
Tabulate the three results for every element and classify each as metal, non-metal or neither clearly.

What you should see

Copper, zinc, magnesium, iron and aluminium are shiny when rubbed, light the tester and bend without breaking. Sulfur is dull yellow, does not light the tester and crumbles. Graphite is the exception that tests the rule: it is a non-metal yet it lights the tester, although it snaps and is only dully shiny. Silicon, a metalloid, looks metallic but is brittle and conducts only weakly. The learner knows it worked when every metal passes all three tests, sulfur fails all three, and graphite and silicon are recorded as mixed results rather than forced into a group.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Every element that conducts electricity is a metal.
Metals and non-metals are opposite in every property.
Anything shiny is a metal.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science 7–10 Syllabus (2023)SC4-PRT-01 SC4-WS-01
Australian Curriculum v9AC9S8I03

Sources

The pages the author read to write this activity.

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