The not so rare ‘rare earth elements’Sub-topic 4.5 is very straightforward and it clearly states the trends should be limited to s and p block metals. As I point out in the teaching tips below there is a problem with the p block metal trends in group 14 as although tin has a smaller atomic radius than lead (1.40 x 10-10 m compared to 1.45 x 10-10 m according to the IB data booklet) it has a lower melting point (232...