CAIE A Level Chemistry 9701 · The Periodic Table: chemical periodicity
The elements sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon are in Period 3 of the Periodic Table. Their melting points vary considerably across the period. Phosphorus exists as molecules, sulfur as molecules, chlorine as molecules, and argon as single atoms.
Compare the melting points and electrical conductivity of these elements, and explain the variations in terms of their structure and bonding.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
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