CAIE A Level Chemistry 9701 · The Periodic Table: chemical periodicity
The melting points of the elements sodium to argon in Period 3 are shown.
| Element | Na | Mg | Al | Si | P | S | Cl | Ar |
|---|---|---|---|---|---|---|---|---|
| Melting point / K | 371 | 922 | 933 | 1687 | 317 | 388 | 172 | 84 |
Explain the variation in melting point across these elements, making clear the structure and bonding responsible for the pattern.
7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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