Year 8 Science · Unit 2 · Lesson 1
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Learning Goals
1. What is the smallest piece of copper that you can still call copper? State what you would have if you split it.
Match each term to an example
Write the matching letter in the middle column. Each letter is used once.
| Term | Letter | Example |
|---|---|---|
| Matter | A. Muddy water: soil and water that can be separated again by filtering. | |
| Element | B. Everything in your classroom, from the desks to the air: it all has mass and takes up space. | |
| Compound | C. The smallest piece of copper that still behaves like copper. | |
| Mixture | D. A diamond: made of only one type of atom, carbon. | |
| Atom | E. Carbon dioxide: carbon and oxygen atoms bonded in fixed proportions. |
Odd one out
In each row, three substances are the same type (element, compound or mixture) and one is not. Circle the odd one out and write what type it is.
| Row | Substances | Odd one out is a… |
|---|---|---|
| 1 | neon (Ne) · copper (Cu) · ammonia (NH₃) · nitrogen gas (N₂) | |
| 2 | pure water (H₂O) · soil · milk · orange juice | |
| 3 | glucose (C₆H₁₂O₆) · table salt (NaCl) · carbon dioxide (CO₂) · sulfur (S) |
Cause and effect
Scenario: a balloon in a hot car
A party balloon full of air is left on the back seat of a car on a hot day. By the afternoon the balloon is tighter and slightly bigger.
Complete the chain using the particle model. Each box is caused by the box before it.
States at room temperature
A substance is solid below its melting point, liquid between its melting point and boiling point, and gas above its boiling point.
| Substance | Melting point (°C) | Boiling point (°C) | State at 25 °C |
|---|---|---|---|
| Mercury (Hg) | −39 | 357 | |
| Oxygen (O₂) | −218 | −183 | |
| Water (H₂O) | 0 | 100 | |
| Copper (Cu) | 1085 | 2562 | |
| Bromine (Br₂) | −7 | 59 |
Source: standard data, rounded.
2. Complete the last column of Table 1. Then name the one substance in the table that is a compound, and explain how you can tell from its formula.
3. A student says: “Elements are always solids, and compounds are always liquids.” Use two rows of Table 1 to show the student is wrong. Then use the particle model to compare the particles of oxygen and copper at 25 °C.
4. A pure iron sample contains iron, and so does your blood. The pure iron sample is grey and magnetic. The iron in blood is part of a large compound called haemoglobin, and it does not behave like the pure metal. Explain why both contain the same element, iron, even though they behave so differently.
Warm Up
1. One copper atom. If you split it you would have protons, neutrons and electrons, which are no longer copper. [2 marks]
Match each term to an example
Matter → B; Element → D; Compound → E; Mixture → A; Atom → C.
Odd one out
Row 1: ammonia (NH₃) is a compound; the others are elements. Row 2: pure water (H₂O) is a compound; the others are mixtures. Row 3: sulfur (S) is an element; the others are compounds.
Cause and effect
Box 2: the air particles inside gain energy and move faster. Box 3: the particles hit the inside of the balloon harder and more often, and spread further apart.
Go Deeper
2. Mercury: liquid. Oxygen: gas. Water: liquid. Copper: solid. Bromine: liquid. The compound is water: its formula H₂O has two different symbols, so it contains two elements chemically bonded; the others each have only one symbol. [3 marks: 1 all five states (0 if two or more wrong); 1 water; 1 reason from the formula]
3. Any two rows as evidence, for example: mercury and bromine are elements but are liquids; oxygen is an element but is a gas. Oxygen particles are far apart and move freely in all directions; copper particles are packed tightly in fixed positions and only vibrate. [4 marks: 2 for two pieces of evidence; 1 oxygen particles; 1 copper particles]
Show What You Know
4. Marking guide (points expected): 1 an element is made of only one kind of atom, and iron atoms are iron atoms wherever they are, not decided by how the sample looks; 1 the pure iron sample is the element iron, made only of iron atoms; 1 haemoglobin is a compound, with iron atoms chemically bonded to atoms of other elements; 1 a compound has different properties from its elements, so iron in haemoglobin does not behave like the pure metal; 1 the iron atoms themselves are the same element in both; only their chemical surroundings are different. [5 marks]
Common error to watch for: saying iron in blood “is a different kind of iron”. The atoms are the same element; what changes is the chemical context they are in.