If you search through Tom Lehrer's Elements Song, you will note that "aluminum" is the odd one out; there is no other element (other than "lanthanum", which is the same both sides of the Atlantic) pronounced in the US as "somethingum", rather than "somethingium".

I have to admit that I would have difficulty in pronouncing "rubidum", "osmum", "helum", "ytterbum" or "sodum" while keeping a straight face.

Has anyone any idea when, where and why the American chemists dropped the "i" from "aluminium" (or was it we hide-bound Brits who put it into "aluminum") ?