Solid sodium conducts electricity. Sodium oxide conducts electricity when molten but not when solid.

1. (a)(i)Name the type of bonding present in sodium and in sodium oxide. bonding in sodium bonding in sodium oxide[1]
2. (a)(ii)Explain how solid sodium conducts electricity.[1]
3. (a)(iii)Explain why sodium oxide conducts electricity when molten.[1]
4. (b)(i)Write an equation for the reaction of sodium with cold water.[1]
5. (b)(ii)Write an equation for the reaction of sodium oxide with cold water.[1]
6. (b)(iii)Complete Table 1.1. Do not refer to temperature changes when considering observations for these reactions. Table 1.1 sodium sodium oxide one similarity in observation on addition to cold water one difference in observation on addition to cold water [2]
7. (c)State the oxidation number of the Period 3 elements bonded to Cl in NaCl and PCl5. Explain the difference in the oxidation number.[2]
8. (d)Table 1.2 shows melting points of some oxides. Table 1.2 oxide melting point/°C SO2 -73 H₂O 0 SO3 17 SiO2 1610 MgO 2852 Al2O3 2072 A student suggests the following hypothesis. The higher the oxidation number of the element combined with oxygen, the higher the melting point of the oxide. Use Table 1.2 to deduce if this hypothesis is true or false or if there is not enough information to make a conclusion. Explain your answer.[2]