When a question supplies data about several materials, the best answer quotes the data that matches the stated purpose. It then uses the structure to explain why that property appears.
This lesson is part of energy evidence and industrial chemistry reasoning. The structure ideas come from chemical bonding.
What is the method?
Follow four steps every time.
- Underline the purpose in the question, for example “base of a cooking pot”.
- List the properties that the purpose needs.
- Find the values for those properties in the table.
- Write claim, evidence and reason, with the structure in the reason.
Worked example: three invented materials
An original table about materials for the base of a cooking pot.
| Material | Structure given | Melting point (°C) | Conducts heat | Brittle or malleable |
|---|---|---|---|---|
| X | Metal, ordered atoms with delocalised electrons | 660 | Yes | Malleable |
| Y | Simple molecules, weak forces between them | 80 | No | Brittle |
| Z | Giant ionic lattice | 800 | No when solid | Brittle |
Purpose: a cooking pot base must conduct heat and be shaped into a flat sheet without cracking, and must not melt on a hot stove.
Claim: X is the most suitable.
Evidence: X conducts heat, is malleable and has a melting point of 660 °C. Y melts at only 80 °C and does not conduct heat. Z does not conduct heat when solid and is brittle.
Reason: X is a metal, so its delocalised electrons carry heat through the material, and its layers of atoms can slide without breaking the bonding. The strong attractions in the structure give a melting point well above the temperature needed for cooking.
The mistake that costs marks
The common slip is to answer from everyday experience: “metals are used for pots”. This may be true, but it does not use the table.
| Answer | Why it scores |
|---|---|
| “X, because metals are used in pots.” | Little or none: no data and no structure |
| “X, because it conducts heat, is malleable and melts at 660 °C, which suits a stove.” | Full: choice, evidence and structure reason |
Quote at least two values from the table, and relate each to the stated purpose.
Check yourself
Use the table above. A kitchen spoon handle must not conduct heat and must not melt in hot water at about 90 °C. Which material suits best, and why?
Answer
Claim: none of the three is fully suitable, so the handle needs a material outside this table.
Evidence: Y does not conduct heat, which a handle needs, but it melts at 80 °C, below the 90 °C of the hot water. X conducts heat well, which is the opposite of what a handle needs. Z does not conduct heat when solid and melts at 800 °C, but the table shows it is brittle, so a thin handle could crack.
Reason: Y has weak forces between its molecules, so little energy is needed to soften it, while X has delocalised electrons that carry heat along the handle. A good answer states which property fails for each material instead of forcing a choice.
What to study next
Finish this section with comparing process conditions using classroom evidence. The claim evidence and explanation revision desk gives you more practice with the structure.
If you want a teacher to check how you use supplied data, see online one-to-one Chemistry tuition.