Purpose
Use provided data to discover the organisation of the periodic table for yourself, rather than being told it.
Materials
- Data cards for 20 elements: atomic number, atomic radius, melting point, reactivity notes — element names removed
Procedure
- Working in pairs, sort the cards into groups by whatever pattern you find.
- Write down the rule you used. Be specific enough that another pair could apply it.
- Trade rules with another pair and sort their cards by your rule.
- Only now, reveal the names and compare your arrangement to the real table.
This is what Mendeleev did
He had no idea electrons existed. He sorted cards by properties and trusted the pattern enough to leave gaps for elements nobody had found. You are repeating the method, not the memorisation.
Sample data
| Card | Atomic number | Radius (pm) | Melting point (°C) | Reacts with water? |
|---|---|---|---|---|
| A | 3 | 152 | 181 | Vigorously |
| B | 11 | 186 | 98 | Violently |
| C | 19 | 227 | 63 | Explosively |
| D | 9 | 42 | −220 | — |
| E | 17 | 79 | −102 | — |
| F | 10 | 38 | −249 | No |
Analysis
- What happens to atomic radius as you go down a column? Explain it using shells — see The Bohr-Rutherford Model.
- Cards A, B, and C get more reactive going down. Cards D and E get less reactive going down. Why do the two families behave in opposite directions?
- Predict the melting point and radius of the element below C. Then look it up.
Hand in
- Your sorting rule, written before the reveal
- Your arrangement compared with the real table
- Analysis answers, including your prediction and how close it was
Curriculum connection
C2.5
investigate the physical and chemical properties of elements, and use their findings to relate these properties to the organization of the periodic table, classify elements, and identify patterns in the periodic table
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C2.4
explain the relationship between the position of an element in the periodic table and the structure of its atoms, using models
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A1.1
apply a scientific research process and associated skills to conduct investigations, making connections between their research and the scientific concepts they are learning
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