1a6 marks
This question is about the elements in Period 3 of the Periodic Table, and some of their compounds.
The atomic radii of six of the elements are given.
| Symbol | Na | Mg | Al | Si | P | S | Cl | Ar |
| Atomic number |
11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| Atomic radius / nm |
0.191 | 0.160 | 0.130 | 0.102 | 0.099 | 0.095 |
i)
Plot a graph of atomic radius against atomic number.
(2)
ii)
Use the graph to estimate the atomic radius of silicon, Si.
(1)
iii)
Suggest an explanation for the decrease in atomic radius as atomic number increases across a period.
(3)
1b6 marks
The melting temperatures of sodium, sodium chloride and chlorine are given in the table.
Complete the table to show the type of structure, the type of bond or force broken on melting and the particles involved.
| Substance | Sodium | Sodium chloride | Chlorine |
| Melting temperature / °C | 98 | 801 | −101 |
| Type of structure | giant | simple molecular | |
| Type of bond or force broken on melting | |||
| Particles involved | chlorine molecules |
1c4 marks
Solid phosphorus(V) chloride contains PCl4+ ions.
i)
Draw a dot-and-cross diagram of a PCl4+ ion.
Show only outer shell electrons.
(1)
ii)
Predict the shape of a PCl4+ ion.
Justify your answer.
(3)
Shape ............................................................................................
Justification
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