The Period 3 elements show trends in physical and chemical properties across the period.

1. (a)(i)Explain why the elements Na to Al are good electrical conductors.[1]
2. (a)(ii)Explain why the elements P, S and Cl do not conduct electricity.[1]
3. (b)Fig. 2.1 shows the variation in melting point of the Period 3 elements Si to Cl. [Figure 2.1] The Period 3 elements Si to Cl are all non-metals. Explain why there is a large difference between the melting point of Si and the melting points of P, S and Cl.[2]
4. (c)Table 2.1 gives some information about some Period 3 chlorides. Row B refers to the pH of the solution that forms when the Period 3 chloride is added to water. [Table 2.1] Complete Table 2.1. You may use the following abbreviations. I = ionic, C = covalent, M = metallic G = giant, S = simple[4]
5. (d)(i)Write an equation for the formation of AlCl₃ from its elements.[1]
6. (d)(ii)Write an equation for the formation of H₃PO₄ from PCl₅.[1]
7. (e)(i)S₂Cl₂(l) reacts with Cl₂(g) in a reversible reaction to form SCl₂(l). Under certain conditions, a dynamic equilibrium is established. S₂Cl₂(l) + Cl₂(g) ⇌ 2SCl₂(l) ΔH = −41 kJ mol⁻¹ State what is meant by dynamic equilibrium.[1]
8. (e)(ii)Identify the condition necessary to establish dynamic equilibrium.[1]
9. (e)(iii)S₂Cl₂(l) is yellow and SCl₂(l) is red. S₂Cl₂(l) + Cl₂(g) ⇌ 2SCl₂(l) ΔH = −41 kJ mol⁻¹ State what is observed when the following changes are made to an equilibrium mixture of S₂Cl₂(l) and SCl₂(l). Explain your answers. • The equilibrium mixture is warmed gently. observation explanation • The overall pressure of the equilibrium mixture is increased. observation explanation[4]
10. (f)(i)Aqueous MgCl₂ reacts with aqueous Na₂CO₃ to form a white precipitate. Upon heating, the white precipitate undergoes thermal decomposition. Construct an equation to show the reaction of aqueous MgCl₂ with aqueous Na₂CO₃. Use state symbols in your equation.[2]
11. (f)(ii)Identify the products of the thermal decomposition of the white precipitate.[1]
12. (f)(iii)State the trend in thermal stability of the Group 2 carbonates down the group.[1]

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