Group 12 / IIB; Scandium Group

The scandium group contains beside yttrium (Y) lanthanium (La) and actinium (Ac) both as individual elements and as place marker for the two groups:
The lanthanoids together with scandium and yttrium (Y) comprise the rare earth elements. These elemet have become rather famous recently (2011) since China has a de-facto monopoly on these elements, When it started raising then prices in the time-honored capitalist way, the world at large suddenly realized how important those elements are for High-Tech applications
Yttrium, for example, is needed for:
  • Stabilizing the zirconia used in many sensors or fule cells. In this case you add yttrium oxide (Y2O 3).
  • Producing the red color in fluorescent lights (and now in some LED lights) needed to get white in the end.
  • Enabling high-temperature superconductor; e.g in the now famous YCu2Ba3O7
  • .

Neodymium, to give another example, is crucial for strong magnets and thus needed in large quantities, e.g. for modern generators.
  The actinoids are essentially artificially produced radioactive elements not found in nature.
 
Table of Basic Data
Name
(German)		 Scandium
Scandium		 Yttrium
Yttrium 		Lanthan
Lanthanum 		Actinium
Actinium
Atomic number 21 39 57 89
Atomic mass [u] 44,95591 88,90585 138,9055 227,0278
Melting point [K] 1812 1796 1193 1320
Melting point [oC] 1539 1523 920 1047
Melting point [oF] 2802 2773 1688 1917
Boiling point [K] 3105 3610 3727 3470
Density [g/cm3] 2,99 4,47 6,16 10,07
Ionization energy [eV] 6,54 6,38 5,577 6,9
Electro-negativitiy 1,2 1,1 1,1 1,0
Atomic radius [pm] 160,6 181 187,7 187,8
Ionic radius [pm] 83 106 122 118
Oxidation numbers 3 3 3 3
Lattice typ
Transformation temp. [oC]		 hp
-		 hcp
-		 fcc
350
hcp		 ?
Lattice constant [Å]
(a or c)		 ? 3,66
5,81		 3,76
6,06		 ?
Young's - Modul us [GPa] ? ? 37,5 ?
Therm. expansion coefficient a
[10-6K-1]
?
?
5,8
?
 
In case of doubt all numbers are for room temperatures
fcc = face centered cubic; lattice const. = a
bcc = body centered cubic
sc = simple cubic
hp = simple hexagonal
hcp = hexagonal close packed; lattice constants a and c.
op = simple orthorhombic, monoclinic, triclinic
tp = simple tetragonal
dia = diamond structure
r = trigonal or rhomboedral trigonal

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