OCR A Jan 2009 Paper 1 Q4

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The table below shows the melting points and atomic radii of the elements in Period 3, Na to Cl. 10 element melting point / C Na 98 atomic radius / pm 186 Mg 639 160 Al 660 143 Si 1410 118 44 110 113 102 Cl 101 99 1 pm = 11012 m (a) (i) Explain the difference in melting point for the elements Na and Mg.[3] (ii) Sulfur exists as S8 molecules and chlorine as Cl 2 molecules. Use this information to explain the difference in their melting points.[2] (b) Explain the decrease in the atomic radii across the period from Na to Cl. In your answer, you should use appropriate technical terms, spelt correctly.[3] [Total: 8]OCR 2009<br />

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