A student is given the atomic radii of four consecutive Period 3 elements but the labels have been lost. The values, in a random order, are:
0.110 nm, 0.143 nm, 0.117 nm and 0.160 nm.
The four elements are magnesium, aluminium, silicon and phosphorus.
Deduce which value belongs to magnesium and which belongs to phosphorus.
[2]
Justify your answer using the trend in atomic radius across the period.
[1]