Connect structure to conductivity

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or a browser document for a labeled drawing, table or explanation.
• Worked problem inputs: Salt conducts when dissolved in supplied water but not in the stated solid. Explain why ions alone are insufficient.
• Assessment case 1: A supplied copper model has mobile electrons through a fixed solid structure. What enables current? Which inference or prediction is best supported?
• Assessment case 2: Which scientific label fits the specifically described step or feature? Supplied case: Salt solution’s mobile ions.
• Assessment case 3: Which scientific label fits the specifically described step or feature? Supplied case: Solid salt ions remain in lattice.
• Assessment case 4: Which scientific label fits the specifically described step or feature? Supplied case: Supplied pure nonionic molecular sample lacks carriers.
• Assessment case 5: Which scientific label fits the specifically described step or feature? Supplied case: Dissolved electrolyte carries charge by ions.
• Assessment case 6: Solid metal conducts, while a supplied ionic solid does not until dissolved. What difference fits? Which inference or prediction is best supported?

Learn the idea

Moving charges enable electrical conduction. Metals have mobile electrons; many dissolved ionic substances provide moving ions. A solid ionic lattice can lack mobile charges even though it contains ions.

Metal conduction means mobile electrons carry charge. Solution conduction means mobile dissolved ions carry charge. Fixed-ion solid means ions held in lattice positions. Molecular insulator means few mobile charge carriers in stated sample.

For the supplied mechanism problem, Salt conducts when dissolved in supplied water but not in the stated solid. Explain why ions alone are insufficient. In solution, ions can move and carry charge. In the solid lattice they are held in positions. Conduction requires mobile charge carriers, not merely the presence of charged particles.

1. Read the supplied problem and mark the structures, processes or quantities named: Salt conducts when dissolved in supplied water but not in the stated solid. Explain why ions alone are insufficient.
2. Draw the relevant boundary, pathway or comparison and label it using the scientific ideas above.
3. Write a causal explanation or calculation, showing how each observation supports the result.
4. Compare your reasoning with the worked solution; name a condition that would change or limit the inference.

Check your reasoning

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Take it further

New model: a metal conducts with mobile electrons, while a dissolved electrolyte conducts with mobile ions. Expected: both require moving charge, but carrier types differ.

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