Rare Earth Elements: Their Importance in Understanding Soil Genesis

Table 1

Chemical properties of the rare earth elements, including La, Sc, and Y.

Element	Atomic^1
	Number	Weight	Ground state Configuration^1	Name
Trivalent REE
La	57	138.9055	[Xe]5d^16s^2	Lanthanum
Ce	58	140.12	[Xe]4f^15d^16s^2	Cerium
Pr	59	140.9077	[Xe]4f^36s^2	Praseodymium
Nd	60	144.24	[Xe]4f^46s^2	Neodymium
Pm	61	145	[Xe]4f^56s^2	Promethium
Sm	62	150.36	[Xe]4f^66s^2	Samarium
Eu	63	151.96	[Xe]4f^76s^2	Europium
Gd	64	157.25	[Xe]4f^75d^16s^2	Gadolinium
Tb	65	158.9254	[Xe]4f^96s^2	Terbium
Dy	66	162.50	[Xe]4f^106s^2	Dysprosium
Ho	67	164.9304	[Xe]4f^116s^2	Holmium
Er	68	167.26	[Xe]4f^126s^2	Erbium
Tm	69	168.93	[Xe]4f^136s^2	Thulium
Yb	70	173.04	[Xe]4f^146s^2	Ytterbium
Lu	71	174.967	[Xe]4f^145d^16s^2	Lutetium
Other notable elements
Eu^2+
Ce^4+
Sc^3+	21	44.9559	[Ar]3d^14s^2	Scandium
Y^3+	39	88.9059	[Kr]4d^15s^2	Yttrium
Ca^2+	20	40.078	[Ar]4s^2	Calcium
Mn^2+	25	54.938	[Ar]3d^54s^2	Manganese
Sr^2+	38	87.62	[Kr]5s^2	Strontium
Th^4+	90	232.0381	[Rn]6d^27s^2	Thorium
U^4+	92	238.0289	[Rn]5f^36d7s^2	Uranium

¹:see [1].