1.1. The elements in Period 3 of the Periodic Table show variations in their behaviour across the period.

Fig. 3.1 shows the variation of melting points of the elements across Period 3.

Fig. 3.1

In each of the following parts of this question you should clearly identify the interactions involved and, where appropriate, explain their relative magnitudes.

Explain the general increase in melting point from Na to Al.

1.2. Explain the variation of melting points from P to Ar.

1.3. Explain why Si has a much higher melting point than any of the other elements in the period.

1.4. Going across Period 3, a trend in electronegativity can also be observed. 

i) Define the term electronegativity. 

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ii) Complete Fig. 3.2 to show how electronegativity changes along Period 3. 

Fig. 3.2

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iii) Explain your answer to part (ii).

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