CAIE A Level Chemistry 9701 · The Periodic Table: chemical periodicity

The Periodic Table: chemical periodicity: explain question

Explain4 marksStandard

An unknown element X is in Period 3 of the Periodic Table. It is a grey solid with a metallic lustre. It reacts with oxygen to form an oxide, $\ce{XO2}$ , which is a hard solid with a very high melting point. The oxide does not conduct electricity even when molten. X reacts with chlorine to form a compound $\ce{XCl4}$ , which is a colourless liquid. $\ce{XCl4}$ fumes strongly in moist air, producing $\ce{HCl}$ .

State the most likely group of X in the Periodic Table. Explain, using the information given and your knowledge of chemical periodicity, why the properties of X and its compounds are consistent with this group.

How this question is marked

4 marks, so the mark scheme is looking for about 4 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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