Lesson focus: A pattern of physical properties provides evidence for classifying an elementA substance made of only one type of atom (all with the same atomic number), which cannot be broken down into anything simpler by chemical reactions. as a metalA shiny element that conducts electricity and heat well, such as iron or copper. or non-metalAn element that is usually dull and does not conduct electricity, such as sulfur or oxygen..
Use several observations to classify elements as metals or non-metals, while recognising that individual properties have exceptions.
Build on earlier learning
ElementsYear 7 established that an element contains one type of atom. This lesson uses property patterns to compare different elements.
Practical
Testing metals and non-metals
- Test each element for shine, conductivity (in a circuit with a bulb) and whether it bends or shatters.
- Use the same test for every sample.
Record: A table of properties that classifies each element as a metal or non-metal.
You will be successful when you can…
- Describe common properties of metals and non-metals.
- Use several observations to classify an unfamiliar sample.
- Explain why conductivity alone is not a perfect test.
- Use evidence cautiously when a sample does not fit every general pattern.
Words that carry the science
- element
- A substance containing only one type of atom.
- metal
- An element that belongs to the metallic region of the periodic table and usually shows metallic properties.
- non-metal
- An element outside the metallic region of the periodic table; non-metals have varied structures and properties.
- conductor
- A material that allows electrical charge or thermal energy to transfer readily.
- malleable
- Able to be hammered or pressed into a new shape without shattering.
- brittle
- Likely to crack or shatter rather than bend when a force is applied.
Classify from a pattern of evidence, not one observation
01Elements form two broad property families
Most known elementA substance made of only one type of atom (all with the same atomic number), which cannot be broken down into anything simpler by chemical reactions. are metalA shiny element that conducts electricity and heat well, such as iron or copper.. At room temperature, almost all are solid; mercury is a liquid exception. A freshly exposed metal surface is often shiny, and many metalA shiny element that conducts electricity and heat well, such as iron or copper. are strong, malleableCan be hammered or pressed into shape without breaking, like a sheet of metal. and good conductorA material that lets electricity or heat pass through it easily, like copper..
non-metalAn element that is usually dull and does not conduct electricity, such as sulfur or oxygen. are more varied. Some are gases, one is a liquid at room temperature, and others are brittleBreaks or shatters easily instead of bending, like glass. solids. Solid non-metalAn element that is usually dull and does not conduct electricity, such as sulfur or oxygen. are generally poor conductors and cannot usually be shaped like metals.
02Use several tests together
A reliable classification compares a pattern: electrical conductivity, appearance of a clean surface, response to force and state at room temperature. Evidence is stronger when several independent observations agree.
Tests must be safe and appropriate. Do not taste an unknown sample or handle it unnecessarily. Use a low-voltage circuit for conductivity and existing data where bending, scratching or heating would be unsafe.
03Patterns have exceptions because structure matters
Elements are classified using their atomic identity and position in the periodic table. Property patterns help us predict and test behaviour, but no single property defines every metal or every non-metal.
Later chemistry explains these patterns using bonding and structure. At this stage, the important reasoning is to state the evidence, compare it with the general pattern and acknowledge any result that does not fit.
Classifying an unknown solid
Sample X has a shiny surface after scratching, conducts electricity and flattens when pressed. Classify it from the evidence.
- Identify the relevant observations: shiny when freshly exposed, conducts electricity and changes shape without shattering.
- Compare each observation with the broad patterns: all three are common metallic properties.
- Use cautious language: the evidence supports a metal classification rather than proving it from one test.
- State what would strengthen the conclusion: identify the element or compare additional reliable property data.
How to make the reasoning visible: Sample X is likely to be a metal because three independent observations match the metallic pattern.
Classify four element samples from evidence
The results are illustrative. Treat each row as evidence collected using safe, suitable tests at room temperature.
| Sample | Clean-surface appearance | Response to force | Electrical test | Known element |
|---|---|---|---|---|
| A | Shiny orange-brown | Bends | Lamp bright | Copper |
| B | Dull yellow | Crumbles | Lamp off | Sulfur |
| C | Dark grey | Brittle; marks paper | Lamp on | Carbon (graphite) |
| D | Shiny silver-grey | Bends | Lamp bright | Aluminium |
Classify samples A, B and D. Use at least two observations for each decision.
Why does sample C show that one property is not enough?
Check your understanding
Answer from memory, then check against the suggested answer.
What is an element?
What does malleable mean?
Name two properties commonly shown by metals.
An unknown solid is dull, brittle and does not complete a low-voltage circuit. What classification is best supported?
Diamond and graphite are both forms of carbon. Diamond does not conduct electricity, while graphite does. Explain why this does not make graphite a metal.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
A solid sample is shiny when scratched, bends when pressed and completes an electrical circuit.
Name the metal property shown by each of the three observations.
(3)Explain why one observation on its own is not enough to classify the sample.
(1)Total for this question: 4 marks
Command word: For explainA command word: say how or why something happens, giving reasons with words like "because" or "so"., connect every observation to the classification and include the reason that several observations are needed.