Page "Lanthanide" Paragraph 2

The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide.

All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell ; lutetium, a d-block element, is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen.

All lanthanide elements form trivalent cations, Ln < sup > 3 +</ sup >, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.