Abundances of the elements 3.1.3



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3.1.3 Abundances of the elements

This table gives an indication of the abundances of the elements in nature. Parts per million, by mass, are denoted by ‘ppm’, whereas abundances stated to be in ‘atoms’ are numbers of atoms per 10⁶ atoms of silicon. The values for sea water and for crustal rocks are from Turekian (1970). Those for stony meteorites are mean values for the commoner varieties of ordinary chondrites taken from Mason (1971) and those for iron meteorites are from Brown (1949) (major elements), from Smales et al. (1968) (trace elements) or from Mason (1971). The values for trace elements in iron meteorites are exceedingly variable and the results given are mean values for median octahedrites. Values for the Sun and Solar System are taken from Grevesse and Anders (1988), except for the solar iron abundance taken from Holweger et al. (1991). The accuracy of the solar abundances varies between ± 10% and a factor of 2 or worse, the latter cases being marked with a colon. The Solar System abundances, based mainly on carbonaceous chondrite meteorites, are generally accurate to ± 10% or better, and they refer to the time of formation of the Solar System allowing for radioactive decay of uranium and thorium. Solar System abundances based on other sources (solar or nearby galactic emission nebulae) are shown in parentheses.

Abundances given for some elements in the Sun are different from those given for the Solar System and in particular this applies to lithium which has been largely destroyed in the Sun owing to thermonuclear reactions during the Sun's lifetime. Other differences between abundances for the Sun and for the Solar System are mainly due to uncertainties in the determinations, especially for the Sun.

Solar System abundances are quite similar to those found in most stars and interstellar material in our neighbourhood and in corresponding parts of other galaxies where, however, minor variations (within a factor of 3 or so either way) may occur in the relative amounts of hydrogen and helium, on the one hand, and carbon and heavier elements on the other. This reflects the fact that hydrogen and the bulk of helium are thought to be relics from the ‘Big Bang’, whereas heavier elements (and a minority of the helium) result from nuclear reactions in stars or in the interstellar medium. Carbon and heavier elements tend to be relatively more abundant in the central regions of large galaxies (such as our own) than in their outer parts or in small galaxies; in stars belonging to the outer spheroidal halo of our Galaxy carbon and heavier elements may be deficient by factors of up to 1 000 or more (relative to hydrogen and helium) when compared to Solar System values, and among these elements, carbon, nitrogen, iron and elements such as barium (resulting from the ‘slow’ neutron capture or s-process in the progenitor stars) can be deficient by larger factors than oxygen, magnesium and other ‘α-particle’ elements synthesised in massive stars which undergo supernova explosions after 10 million years or so. Peculiar over- and under-abundances of various elements can also be found in some highly evolved stars as a result of internal nuclear reactions, and in the surface layers of certain stars where diffusive separation of elements seems to have occurred.

The composition of the atmosphere is from Kuiper (1949) with corrections from Glueckauf and Kitt (1956).

References

H. Brown (1949) Rev. Mod. Phys., 21, 625.
Glueckauf and Kitt (1956) Proc. Roy. Soc. A, 234, 557.
N. Grevesse and E. Anders (1988) in Cosmic Abundances of Matter (ed. J. Waddington), Amer. Inst. Phys.,
New York, p. 1.
H. Holweger, A. Bard, A. Kock and M. Kock (1991) Astron. Astrophys., 249, 545.
G. P. Kuiper (ed.) (1949) The Atmospheres of the Earth and Planets, Univ. of Chicago Press.
B. Mason (1971) Handbook of Elemental Abundances in Meteorites, Gordon and Breach, New York.
A. A. Smales, D. Mapper and K. F. Fouche (1968) in Origin and Distribution of the Elements (ed. L. H. Ahrens),
Pergamon Press, London, pp. 329–344.
K. K. Turekian (1970) in McGraw-Hill Encyclopedia of Science and Technology, 4, 627.

Abundances

At.
No.

Element

Sea water

μg dm⁻³

Crustal

rocks

ppm

Meteorites

Sun
atoms

Solar
system
atoms

Stony

ppm

Iron

ppm

1.1 × 10⁸

—

2.8 × 10¹⁰

(2.8 × 10¹⁰)

0.007 2

—

2.7 × 10⁹

(2.7 × 10⁹)

1.7 × 10²

1.7

—

0.4

0.000 6

2.0

0.040

—

0.4

0.7

4.4 × 10³

7.0

2.1

—

2.8 × 10⁴

—

1.0 × 10³

1.1 × 10³

1.0 × 10⁷

(1.0 × 10⁷)

1.6 × 10⁴

3.1 × 10⁶

(3.1 × 10⁶)

8.8 × 10⁸

3.7 × 10⁵

—

2.4 × 10⁷

(2.4 × 10⁷)

1.3 × 10³

4.6 × 10²

1.2 × 10²

—

10³:

8.5 × 10²

0.12

—

3 × 10⁶

(3 × 10⁶)

1.1 × 10⁷

2.3 × 10⁴

6.2 × 10³

—

6.0 × 10⁴

5.7 × 10⁴

1.3 × 10⁶

2.8 × 10⁴

1.5 × 10⁵

3.2 × 10²

1.0 × 10⁶

1.1 × 10⁶

8.0 × 10⁴

1.0 × 10⁴

8.3 × 10⁴

8.5 × 10⁴

2.9 × 10³

2.7 × 10⁵

1.8 × 10⁵

1.0 × 10⁶

1.0 × 10³

1.1 × 10³

2.2 × 10³

8 × 10³

1.0 × 10⁴

9.0 × 10⁵

3.0 × 10²

2.1 × 10⁴

3.6 × 10²

4.5 × 10⁵

5.2 × 10⁵

1.9 × 10⁷

1.9 × 10²

—

9 × 10³:

5.2 × 10³

4.5 × 10²

—

(1.0 × 10⁵)

3.9 × 10⁵

1.7 × 10⁴

8.8 × 10²

—

3.7 × 10³

3.8 × 10³

4.1 × 10⁵

5.1 × 10⁴

1.2 × 10⁴

5.0 × 10²

6.4 × 10⁴

6.1 × 10⁴

< 0.004

7.6

—

8.6 × 10³

6.4 × 10²

1.0 × 10²

2.7 × 10³

2.4 × 10³

1.9

1.7 × 10²

2.8 × 10²

2.9 × 10²

0.2

3.6 × 10³

1.3 × 10⁴

1.9

1.0 × 10³

2.3 × 10³

3.0 × 10²

6.9 × 10³

9.5 × 10³

3.4

5.8 × 10⁴

2.5 × 10⁵

9.1 × 10⁵

9.0 × 10⁵

0.39

7.0 × 10²

6.3 × 10³

2.3 × 10³

6.6

1.5 × 10⁴

6.7 × 10⁴

5.0 × 10⁴

1.3 × 10²

4.5 × 10²

5.2 × 10²

1.1 × 10³

1.3 × 10³

0.03

5.1

0.06

1.3

1.2 × 10²

2.6

2.0

1.8

—

6.6

0.090

0.05

8.0

—

6.7 × 10⁴

4.0

0.4

—

0.21

—

1.2 × 10²

4.0

—

7.0

8.1 × 10³

4.5 × 10²

10.0

—

0.001 3

0.35

2.2

—

4.9

4.6

0.026

1.4 × 10²

11.2

11.4

0.015

0.1

0.2

0.7

0.70

1.2

1.5

7.3

2.3

2.6

Unstable with short period

—

0.9

1.9

—

0.23

4.1

0.4

0.34

—

0.003

0.84

3.8

1.4

0.28

0.08

0.085

0.035

0.2:

0.49

0.11

0.18

0.06

0.02

2.0

1.6

—

0.2

0.004

0.010

1.3:

0.19

0.81

1.5

0.65

3.9

0.33

0.2

0.10

0.34

0.3:

0.31

—

1.7

—

4.9

0.5

0.036

0.6

—

0.9

0.047

—

4.8

0.30

1.6

0.08

—

0.37

3.8 × 10²

3.5

—

3.8

4.5

0.003 4

0.32

—

0.5

0.44

0.001 2

0.86

—

1.0

1.1

0.000 64

0.12

—

0.14

0.17

0.002 8

0.59

—

0.9

0.83

Unstable with short period

0.000 45

7.7

0.19

—

0.3

0.26

0.000 13

2.2

0.07

—

0.09

0.097

0.000 70

6.3

0.28

—

0.37

0.33

0.001 4

1.0

0.048

—

0.02:

0.060

0.000 91

8.5

0.31

—

0.35

0.40

0.000 22

1.6

0.07

—

0.05:

0.089

0.008 7

3.6

0.20

—

0.24

0.25

0.000 17

0.52

0.03

—

0.03:

0.038

0.000 82

3.4

0.19

—

0.34

0.25

0.000 15

0.8

0.033

—

0.15:

0.037

<0.008

0.24

—

0.21

0.15

<0.002 5

2.4

0.022

0.06

—

0.038

<0.001

1.0

0.15

8.1

0.36:

0.13

—

0.000 4

0.058

0.85

—

0.05

—

0.000 2

0.77

7.6

0.8

0.67

—

0.000 2

0.64

3.0

0.6

0.66

—

1.1

1.8:

1.34

0.011

0.002

0.20

1.8

0.3:

0.19

0.15

0.02

0.13

—

0.34

—

0.47

0.003

—

0.2:

0.19

0.03

0.30

2.0

3.1

0.02

0.004

0.012

0.5

—

0.14

84–89

Po–Ac

Unstable with short period

0.001 5

5.8

0.044

0.04

0.05

0.045

Unstable with short period

3.3

1.6

0.015

0.007

—

0.018

93–102

Np–No

Unstable with short period

B.E.J.Pagel

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