The elements silicon, phosphorus and sulfur are in Period 3 of the Periodic Table. (b) Table 1.1 shows some properties of the elements Si to S. The first ionisation energy of P is not shown. [Table 1.1] property | Si | P | S ---|---|---|--- total number of electrons in s subshells | | | total number of electrons in p subshells | | | first ionisation energy/kJ mol-1 | 786 | | 1000 formula of most common chloride | SiCl4 | PCl5 | SCl2

1. (a)(i)Describe the variation in atomic radius from silicon to sulfur.[1]
2. (a)(ii)The melting point of silicon is 1410°C. The melting point of sulfur is 113°C. Explain this difference.[3]
3. (b)(i)Complete Table 1.1 to show the total number of s and p electrons in an atom of Si, P and S.[2]
4. (b)(ii)Construct an equation to represent the first ionisation energy of Si.[1]
5. (b)(iii)Three possible values for the first ionisation energy of P are given. 619 kJ mol-1 893 kJ mol-1 1060 kJ mol-1 Circle the correct value. Explain your choice, including a comparison of your chosen value to those of Si and S.[4]
6. (b)(iv)SiCl4 and PCl5 each react with water, forming misty fumes. Identify the chemical responsible for the misty fumes.[1]
7. (b)(v)Predict the shape of the SCl₂ molecule.[1]

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