Elemental composition of the earth

The approximate elemental composition of the earth s inorganic mineral surface is reported in Table 3,2. Elemental composition alone, however, cannot justify the unique properties of soil and how such properties influence the soil and water environment. The component that explains many of the physical and chemical properties of soil is the molecular arrangement of elements, forming structures with unique physicochemical properties. Soil mineral structures are briefly discussed below. 

TABLE 3.2. Approximate Elemental Composition of the Earth s Outer-Surface Layer... 

Correns (1969) has given a vivid description of the development of ideas concerning the elemental composition of the earth s crust and the discovery of the elements. Only 150 years ago (1821), the term chemistry of the earth was used by Berzelius, as synonymous with the term mineralogy . In the middle of the last century (1845 — 1854), G. Bischof published his three-volume work Lehrbuch der chemischen und physikalischen Geologie . Chemists (like Bunsen) and earth scientists became aware of the potential of a chemical approach to the problems of earth and hydrosphere. Clarke published the first edition of his Data of Geochemistry in 1908 and the fifth edition (1924) remained a standard reference for many years. Vernadsky (1863—... 

Major element composition of the Earth s primitive mantle... 

Li J. and Agee C. B. (2001) Element partitioning constraints on the light element composition of the Earth s core. Geophys. Res. Lett. 28, 81-84. 

Silicon constitutes 28% of the elemental composition of the earth s crust and is the most abundant crustal element after oxygen (47%). Silicates, compounds which contain Si04 tetrahedra in the crystal lattice, account for about one-third of all known mineral species and about 95% of the earth s crust. In view of this high abundance of silicate minerals in the near-surface crustal regime, it is perhaps not surprising that organisms (which also inhabit the near-surface environments of the earth) have found numerous ways of interacting with siliceous materials. 

TABLE 3.1 Major element compositions of the Earth s mantle as calculated by the different models discussed in the text. ... 

Because the heavier elements are formed in localized areas of the universe, the distribution of these elements is uneven. The elemental composition of the earth, for example, is very different from most of the rest of the universe. Table 18.5 lists the percent abundance of elements in the earths crust, waters, and atmosphere. Note that eleven elements make up over 99% of the planets mass. Some elements that play major roles in our culture and technology—such as copper, tin, zinc and gold—are actually very rare. 

How has the diagram such as Fig. 13.1 been determined How can you determine the relative quantities of elements in the universe It would be very hard, virtually impossible, to determine the exact elemental composition of the Earth, let alone that of the whole universe. How then can we believe such a diagram as Fig. 13.1 Or how can they (those who put forward such a diagram) claim that the diagram is a meaningful estimate These are only a few questions that can be raised for this kind of diagram. Think about it. 

Occurrence in Nature. About 99.6% of the earth s mass results from 32 of the chemical elements. The remaining 0.4% is apportioned among 64 elements, all of which are present as traces. Iodine is one of these 64. Estimates about abundance of the constituent elements of the Hthosphere place iodine 46th on a restricted Hst of 59 elements (37 very rare elements are excluded) and 61st on a Hst in which 96 elements are included. Iodine is, indeed, one of the scarcest of the nonmetaUic elements in the total composition of the earth (3). 

The composition of the Earth was determined both by the chemical composition of the solar nebula, from which the sun and planets formed, and by the nature of the physical processes that concentrated materials to form planets. The bulk elemental and isotopic composition of the nebula is believed, or usually assumed to be identical to that of the sun. The few exceptions to this include elements and isotopes such as lithium and deuterium that are destroyed in the bulk of the sun s interior by nuclear reactions. The composition of the sun as determined by optical spectroscopy is similar to the majority of stars in our galaxy, and accordingly the relative abundances of the elements in the sun are referred to as "cosmic abundances." Although the cosmic abundance pattern is commonly seen in other stars there are dramatic exceptions, such as stars composed of iron or solid nuclear matter, as in the case with neutron stars. The... 

Attention — this is not a textbook It is also not meant to replace one. Nevertheless, there is a lot to be learnt, albeit in a different manner from that in which chemistry is normally presented. The initial question is old and simple "What does the world consist of " This leads to the next question "Who were the researchers who discovered this " They should not be forgotten by us, who take almost for granted all the advantages of progress. After all, the discovery of the 92 elements that occur in the universe and that can also be found on Earth is one of the greatest accomplishments of human intellectual curiosity. Through these discoveries we know what stars are made of, we know the composition of the Earth, and we know which elements are essential for life. 

Major-element compositions (weight ratios of Mg/Si and Al/Si) for mantle rocks (peridotites) and estimates of the primitive mantle composition of the Earth compared with various groups of chondrites and the Sun. No mixture of chondrite types provides an exact match to the primitive mantle composition, although some carbonaceous chondrites provide the closest match. Modified from Righter et al. (2006). 

Andeisnii, D.L. Composition of the Earth, Science, 367 (January 20. 1939). Cheifas. J. Proton Miciobeain Probes the Elements, Science, 11500 (September 23, 1990). 

Efforts have been made to determine the compositions of both the primitive mantle and depleted materials in the modern mantle. In the approach of Palme and O Neill (2004), the estimated chemistry of the primitive mantle was determined by subtracting the likely elemental concentrations of the Earth s core from results on the bulk chemistry of the Earth. The chemistry of the bulk Earth may be derived from chemical data on Cl chondrite meteorites, spectrographs of the Sun, and/or analyses of upper mantle rocks. Based on the chemical properties of an element, assumptions can be made on how much of the element was likely to have accumulated in the core. On the basis of this approach, Palme and O Neill (2004, 14) concluded that the arsenic concentration of the primitive mantle was 0.066 0.046 mg kg-1 (Table 3.3). 

Liu, L.-G. Bassett, W. A. (1986) Chemical and mineral composition of the Earth s interior. In Elements, Oxides, and Silicates. (Oxford Univ. Press), pp. 234—44. Sherman, D. M. (1988) High-spin to low-spin transition of iron(II) oxides at high pressures possible effects on the physics and chemistry of the Lower Mantle. In Structural and Magnetic Phase Transitions in Minerals. (S. Ghose, J. M. D. 

Liu, L.-G. Bassett, W. A. (1986) Chemical and mineral composition of the Earth s interior. In Elements, Oxides, and Silicates. (Oxford Univ. Press), pp. 234—44. 

Turekian and Wedepohl (1961), Vinogradov (1962), Taylor (1964), Ronov and Yaroshevskiy (1969) and Wedepohl (1969) calculated the proportions of all or most elements in the composition of the earth s crust. There are few differences between their resulsts and those of Horn and Adams. 

A preliminary study of the most recent analyses of meteorites of different classes showed that, either for any one class or for the meteorites as a whole the even numbered or helium system elements are very much more abundant than those of the odd numbered or lithium system. For a more detailed study use was made of the data collected by Farrington, who suggests that the average composition of meteorites may represent the composition of the earth as a whole. 

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