Elemental Distributions in the
Universe and the Solid Earth
GLY 4241 - Lecture 2
Fall, 2014
1
Elemental Abundance Expression
•
•
•
•
Number of atoms per million atoms
Weight percent
Volume percent
Relative to abundance of silicon
2
Abundance versus Atomic Number
3
Light Element
Abundance
4
Oddo-Harkins Rule
• For elements heavier than H, the Oddo-Harkins rule holds that
elements with an even atomic number (such as carbon) are more
common than elements with an odd atomic number (such as
nitrogen)
• The effect was first reported by Giuseppe Oddo in 1914 and
William Draper Harkins in 1917
• Elements with odd atomic numbers have one unpaired proton
• During nucleosynthesis, these elements are more likely to
capture another proton, thus increasing their atomic number
• In elements with even atomic numbers, protons are paired, with
each member of the pair offsetting the spin of the other,
enhancing stability
5
Odd-Odd Scarcity
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•
•
•
Li6 7.42 % Li7 92.58%
B10 19.80 % B11 80.20%
K39 93.20 % K40 0.012%
K41 6.73%
Results from the Oddo-Harkins Rule
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Cosmic Abundances
Element
Abundance Element
Abundance
Hydrogen
Helium
Oxygen
Carbon
Neon
2.66 x 1010
1.8 x 109
1.84 x 107
1.11 x 107
2.6 x 106
2.31 x 106
1.06 x 106
1.00 x 106
9.0 x 105
5.0 x 105
Nitrogen
Magnesium
Silicon
Iron
Sulfur
Cosmic Abundances Normalized to Si = 106
7
Hydrogen-Helium Dominence
8
Solar System versus Earth
9
Crustal Abundances in the Earth
Element
Abundance Element
Abundance
Oxygen
46.6
Sodium
2.8
Silicon
27.7
Potassium
2.6
Aluminum 8.1
Magnesium
2.1
Iron
5.0
All Others
1.5
Calcium
3.6
Approximate percentage by weight
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Continental versus Total Crust
Oxide Cont. Crust Total
Crust
Oxide Cont. Crust Total
Crust
SiO2
61.0
59.3
MgO
3.1
4.0
TiO2
0.8
0.9
CaO
5.7
7.2
Al2O3 15.6
15.8
Na2O
3.1
3.0
Fe2O3 2.6
2.6
K2O
2.9
2.4
FeO
3.9
4.4
P2O5
0.3
0.2
MnO
0.1
0.2
Total
100.0
100.0
•
After Mason and Moore, 1982, p.44
11
Different Types of Data
Element
O
Atom %
62.55
Weight %
46.60
Volume %
91.7
Si
21.22
27.72
0.2
Al
6.47
8.13
0.5
Fe
1.92
5.00
0.5
Na
2.64
2.83
2.2
Ca
1.94
3.63
1.5
Mg
1.84
2.09
0.4
K
1.42
2.59
3.1
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