One element that everyone seems to know the value of is gold. Due to the ‘credit crunch’ and the continuing world economic uncertainties the price of gold has increased to nearly US$2000 per ounce. This represents an increase of about 30% over the past few months. Not a bad return for those canny investors who timed it right and moved out of equities (which have recently fallen heavily) and into gold.

However armed with a knowledge of both chemistry and economics and with a modicum of luck and good timing you could have done much better than this by investing in other precious metals.  An investor who bought europium or dysprosium (right) in June this year would have tripled the value of their investment (an increase of 200%) in just three weeks! These two metals belong to a group of metallic elements which does not feature at all on the IB programme - the lanthanides.  It seems odd that the lanthanide elements do not even get a mention, especially as some of them have very particular and important uses. Some of these uses are well-established but many are relatively very recent in origin. For example, cerium oxide has been used for a long time to polish glass but a more modern use is in catalytic convertors. Dysprosium compounds are highly susceptible to magnetization so one of their most recent uses is in computer hard drives and europium oxide is used in television and computer monitors due to its phosphorescent properties. Although some of the lanthanides (sometimes known as rare earth elements) are not actually that rare they are not found concentrated in nature so are expensive to extract and process. Because of their increasing uses in modern technology demand for them has increased. The two countries with the greatest production of lanthanides are the US and China. The rapid increase in price during June was because the Chinese severely cut back on production thus reducing the supply.

I do briefly mention the lanthanides to my students as they are the first f block elements. You could use the lanthanides to check whether Higher Level students really understand the relationship between position in the periodic table and electron configuration. Ask them for the electron configuration of element 61 promethium for example. For the IB under 'Applications & skills in Topic 2.2 both SL and HL  students are actually only required to be able to work out electron configurations for elements up to krypton (Z = 36). However by extrapolation from xenon, promethium, which only has seven more electrons than xenon (Z = 54), is likely to be either [Xe]6s²5d¹4f⁴ (as it is underneath scandium and ytterbium) or [Xe]6s²4f⁵ (as 4f comes after 6s and before 5d) which helps them to understand why the IB stops at krypton.

For those teachers and students who like mnemonics such as OILRIG or Richard of York gave battle in vain” you could even give them “Lazy chemists probably never prosper, some even go to death having erred through youthful lethargy”. Get them to work out that this useless piece of information (!) is a way of remembering: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

For another lanthanide mnemonic and some chemistry take a look at the Nottingham University video (below) on lanthanum (there are also videos from the same series on each of the other lanthanide metals).