The Rare Earth Elements. The REE and the Periodic Table Li 3 H 1 Na K Rb Cs Fr Be Mg Ca Sr Ba Ra Sc...
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The Rare Earth Elements
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Transcript of The Rare Earth Elements. The REE and the Periodic Table Li 3 H 1 Na K Rb Cs Fr Be Mg Ca Sr Ba Ra Sc...
The Rare Earth Elements
The REE and the Periodic Table
Li3
H1
Na
K
Rb
Cs
Fr
Be
Mg
Ca
Sr
Ba
Ra
Sc
Y
La
Ac
Ti
Zr
Hf
Rf
V
Nb
Ta
Cr
Mo
W
Sg
Mn
Tc
Re
Bh
Fe
Ru
Os
Co
Rh
Ir
Ni
Pd
Pt
Ag
Au
Cd
Hg
B
Al
Ga
In
Tl
C
Si
Ge
Sn
Pb
N
P
As
Sb
Bi
O
S
Se
Te
Po
F
Cl
Br
I
At
He
Ne
Ar
Kr
Xe
Rn
11
19
37
55
87
4
12
20
38
56
88
21 22 23 24 25 26 27 28Cu Zn
29 30 31 32
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
36
18
10
2
5 6 7 8 9
1716151413
33 34 35
57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
89 104 105 106 107Hs Mt Ds Uuu Uub Uuq108 109 110 111 112 114
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu58 59 60 61 62 63 64 65 66 67 68 69 70 71
Light REE Heavy REE
Relative Abundance of the REE in the Earth’s Crust Normalized to
Primitive Mantle
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu0.1
1
10
100
Y
LREE
HREE
HREE
The Lanthanide Contraction
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
Ce4+
Eu2+ REE3+
Ioni
c ra
dius
(A
ngst
rom
s)
Y3+
HeavyLightY3+
The Oddo-Harkins Rule
Elements with odd atomic numbers are less abundant in the cosmos than elements with even atomic numbers. This leads to a saw-toothed pattern in plots of element abundance vs atomic number.
During nucleosynthesis 42He is a
basic building block and thus collision of two 4
2He nucleii will produce 8
4Be and collision of a 8
4Be nucleus with a 42He nucleus
will produce 126C and so on.
Post-Archean Australian Shale
RE
E C
onc
ent
ratio
n in
mg
/Kg
RE
E C
onc
ent
ratio
n n
orm
alis
ed
to c
hon
drit
e
The Effect of Normalisation
The normalisation to chondrite smoothes the saw-toothed pattern and makes it possible to observe that relative to chondrite, shales are enriched in the LREE and display a marked negative Eu anomaly.
The Geochemical Twins Ho and YR
EE
in S
amp
le/C
hon
drit
e
Yttrium and Holmium have the same charge 3+ and almost the same ionic radius, 104.0 and 104.1 pm, respectively. By contrast, the neighbours, Dy and Er have radii of 105.2 and 103.0, pm, respectively. Y and Ho should therefore substitute in minerals preserving their mantle ratio of 25.94.
A Positive Ce anomaly in Zircon
The structure of zircon favours the incorporation of the HREE, commonly due to a coupled substitution of REE3+ + P5+ for Zr4+ and Si4+. Ce3+ (115 pm) is too large to substitute into the lattice but as Ce4+ (101 pm) is very similar in size to Yb (100.8 pm)
