Terminology

Definitions?

Rare Earths

La-Lu and Y & Sc occur together in minerals ~ hard to separate from each other

{Th which occurs in many rare earth minerals is sometimes included in the definition}

Lanthanides

Usually taken to indicate the 15 elements from La-Lu or the 14 from Ce-Lu

Actinides

The 15 elements from Ac-Lw or the 14 from Th-Lw

Mnemonics:

Lanthanides

Special Feature - The ICL's 1998 Mnemonic Competition Winner

by Fergus Baillie, Peter Jelfs & Matthew Powell

Lanthanide Chemistry Presents No Problems Since Everyone Goes To Doctor Heyes's Excrutiatingly Thorough Yearly Lectures

Actinides

Some Viewpoints

"Lanthanum has only one important oxidation state in aqueous solution, the +3 state. With few exceptions, this tells the whole boring story about the other 14 Lanthanides"

G.C. Pimentel & R.D. Sprately,

"Understanding Chemistry",

Holden-Day, 1971, p. 862

"These elements (rare earths) perplex us in our researches, baffle us in our speculations and haunt us in our dreams. They stretch like an unknown sea before us - mocking, mystifying and murmuring strange revelations and possibilities"

Sir William Crookes

Address to the British Association, 1887

Due to the increasing technological importance of the rare earths William Crookes's view seems to be returning to fashion!