Earth s crust elements

Sulfur is widely distributed in the Earth s crust. Elemental sulfur is found in sedimentary deposits (domed formations of rock salt, gypsum and limestone, particularly in the Gulf of Mexico, Sicily and Poland) or in deposits of volcanic origin (e.g. in East Asian basins alongside the Philippines and Japan). 

FIGURE P.3 Left the (relative) abundance of Earth s Crust elements right the Earth differentiation in metal core and the oxide/sihcate mantle after [Mineralogy (2001). Lectures Notes of Mineralogy, University of Bristol (Curator Prof D. M. Sherman)]. 

After oxygen, silicon is the most abundant element in the earth s crust, It occurs extensively as the oxide, silica, in various forms, for example, flint, quartz, sand, and as silicates in rocks and clays, but not as the free element, silicon. Silicon is prepared by reduction of silica, Si02- Powdered amorphous silicon can be obtained by heating dry powdered silica with either powdered magnesium or a... 

A gaseous element, oxygen forms 21 % of the atmosphere by volume and is obtained by liquefaction and fractional distillation. The atmosphere of Mars contains about 0.15% oxygen. The element and its compounds make up 49.2%, by weight, of the earth s crust. About two thirds of the human body and nine tenths of water is oxygen. 

Sodium is present in fair abundance in the sun and stars. The D lines of sodium are among the most prominent in the solar spectrum. Sodium is the fourth most abundant element on earth, comprising about 2.6% of the earth s crust it is the most abundant of the alkali group of metals. 

Silicon makes up 25.7% of the earth s crust, by weight, and is the second most abundant element, being exceeded only by oxygen. Silicon is not found free in nature, but occurs chiefly as the oxide and as silicates. Sand, quartz, rock crystal, amethyst, agate, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, hornblende, asbestos, feldspar, clay, mica, etc. are but a few of the numerous silicate minerals. 

Calcium is a metallic element, fifth in abundance in the earth s crust, of which if forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Apatite is the fluorophosphate or chlorophosphate of calcium. 

The element is much more abundant than was thought several years ago. It is now considered to be the 16th most abundant element in the earth s crust. Rubidium occurs in pollucite, leucite, and zinnwaldite, which contains traces up to 1%, in the form of the oxide. It is found in lepidolite to the extent of about 1.5%, and is recovered commercially from this source. Potassium minerals, such as those found at Searles Lake, California, and potassium chloride recovered from the brines in Michigan also contain the element and are commercial sources. It is also found along with cesium in the extensive deposits of pollucite at Bernic Lake, Manitoba. 

Searches for the element on earth have been fruitless, and it now appears that promethium is completely missing from the earth s crust. Promethium, however, has been identified in the spectrum of the star HR465 in Andromeda. This element is being formed recently near the star s surface, for no known isotope of promethium has a half-life longer than 17.7 years. Seventeen isotopes of promethium, with atomic masses from 134 to 155 are now known. Promethium-147, with a half-life of 2.6 years, is the most generally useful. Promethium-145 is the longest lived, and has a specific activity of 940 Ci/g. 

Natural abundance. The natural abundances listed are on an atom percent basis for the stable nuclides present in naturally occurring elements in the earth s crust. 

Table 1. Rare Earths and Other Elements in the Earth s Crust...

They are, potentially or actually, cheap. Most ceramics are compounds of oxygen, carbon or nitrogen with metals like aluminium or silicon all five are among the most plentiful and widespread elements in the Earth s crust. The processing costs may be high, but the ingredients are almost as cheap as dirt dirt, after all, is a ceramic. 

Oxygen occurs free in air in which it forms 21% by volume. It is also found combined with hydrogen in water and constitutes 86% of the oceans, and with other elements such as minerals constituting ca 50% of the earth s crust. In the laboratory it is usually prepared by the thermal decomposition of potassium chlorate in the presence of manganese dioxide catalyst ... 

The seventh element in order of abundance in the Earth s crust is potassium - about the same as sfjdium with similar properties. While sodium is readily available from the ocean, potassium is found and extracted from many mineral formations. About 90 percent of the potassium that is extracted goes to the production of fertilizers. Other purposes for it are ceramics and fire extinguishers for which potassium bicarbonate is better than sodium bicarbonate. 

Oxygen is the most abundant element on earth. The earth s crust is rich in carbonate and silicate rocks, the oceans are almost entirely water, and oxygen constitutes almost one fifth of the air we breathe. Carbon ranks only fourteenth among the elements in natural abundance, but trails only hydrogen and oxygen in its abundance in the human body. It is the chemical properties of carbon that make it uniquely suitable as the raw material forthe building blocks of life. Let s find out more about those chemical properties. 

Its terrestrial abundance has been estimated as 2x10" ppm, which corresponds to a total of only 15g in the top 1km of the earth s crust. Other isotopes have since been produced by nuclear reactions but all have shorter half-lives than Fr, which decays by energetic emission, t j2 21.8 min. Because of this intense radioactivity it is only possible to work with tracer amounts of the element. 

Calcium, as noted above, is the fifth most abundant element in the earth s crust and hence the third most abundant metal after A1 and Fe. Vast sedimentary deposits of CaC03, which represent the fossilized remains of earlier marine life, occur over large parts of the earth s surface. The deposits are of two main... 

None of the three elements is particularly abundant in the earth s crust though several minerals contain them as major constituents. As can be seen from Table 13.1, arsenic occurs about halfway down the elements in order of abundance, grouped with several others near 2 ppm. Antimony has only one-tenth of this abundance and Bi, down by a further factor of 20 or more, is about as unabundant as several of the commoner platinum metals and gold. In common with all the post-transition-element metals. As, Sb and Bi are chalcophiles, i.e. they occur in association with the chalcogens S, Se and Te rather than as oxides and silicates. 

Rhodium and iridium are exceedingly rare elements, comprising only 0.0001 and 0.001 ppm of the earth s crust respectively, and even... 

Nickel is the seventh most abundant transition metal and the twenty-second most abundant element in the earth s crust (99 ppm). Its commercially important ores are of two types ... 

Zinc (76ppm of the earth s crust) is about as abundant as rubidium (78 ppm) and slightly more abundant than copper (68 ppm). Cadmium (0.16 ppm) is similar to antimony (0.2 ppm) it is twice as abundant as mercury (0.08 ppm), which is itself as abundant as silver (0.08 ppm) and close to selenium (0.05 ppm). These elements are chalcophiles (p. 648) and so, in the reducing atmosphere prevailing when the earth s crust solidified, they separated out in the sulfide phase, and their most important ores are therefore sulfides. Subsequently, as rocks were weathered, zinc was leached out to be precipitated as carbonate, silicate or phosphate. 

Apart from the unstable (half-life 2.623 y) of which traces occur in uranium ores, the lanthanides are actually not rare. Cerium (66 ppm in the earth s crust) is the twenty-sixth most abundant of all elements, being half as abundant as Cl and 5 times as abundant as Pb. Even Tm (0.5 ppm), the rarest after Pm, is rather more abundant in the earth s crust than is iodine. 

A photovoltaic cell (often called a solar cell) consists of layers of semiconductor materials with different electronic properties. In most of today s solar cells the semiconductor is silicon, an abundant element in the earth s crust. By doping (i.e., chemically introducing impurity elements) most of the silicon with boron to give it a positive or p-type electrical character, and doping a thin layer on the front of the cell with phosphorus to give it a negative or n-type character, a transition region between the two types... 

Table 1.1 lists the names and symbols of several elements that are probably familiar to you. In either free or combined form, they are commonly found in the laboratory or in commercial products. The abundances listed measure the relative amount of each element in the earth s crust, the atmosphere, and the oceans. 

The metallic element titanium (11) is relatively abundant in nature it accounts for 0.56% of the earth s crust. This number may not seem very impressive until you realize that it exceeds the combined abundances of ten familiar elements H, N, C, P, S, Cl, Cr, Ni, Cu, and Zn. The most important ore of titanium is ilmenite. a mineral commonly found as a deposit of black sand along beaches in the United States, Canada, Australia, and Norway. In ilmenite. titanium is chemically combined with iron and oxygen. The presence of iron makes the ore magnetic. 

Niobium and tantalum are rare elements. The content of niobium and of tantalum in the Earth s crust is lxl0"3 and 2x1 O 4 wt. %, respectively [21]. Niobium and tantalum are encountered in nature together, mostly in the form of oxides that are derived from orthoniobic (orthotantalic), metaniobic (metatantalic) and pyroniobic (pyrotantalic) acids. The main minerals are listed in Table 2, which reveals that the most important source of tantalum and niobium is tantalite-columbite, (Fe,Mn)(Nb,Ta)206. 

Except for argon, the third-row elements make up an important fraction (about 30%) of the earth s crust. Silicon and aluminum are the second and third most abundant elements (oxygen is the most abundant). Both the occurrence and the mode of preparation of each element can be understood in terms of trends in chemistry discussed earlier in this chapter. 

Silicon is the second most abundant element in the earth s crust. It occurs in sand as the dioxide Si02 and as complex silicate derivatives arising from combinations of the acidic oxide Si02 with various basic oxides such as CaO, MgO, and K20. The clays, micas, and granite, which make up most soils and rocks, are silicates. All have low solubility in water and they are difficult to dissolve, even in strong acids. Silicon is not found in the elemental state in nature. 

Oxygen and silicon are the most abundant elements in the earth s crust. Table 25-111 shows that 60% of the atoms are oxygen atoms and 20% are silicon atoms. If our sample included the oceans, hydrogen would move into the third place ahead of aluminum (remember that water contains two hydrogen atoms for every oxygen atom). If the sample included the central core... 

Abundance of elements in earth s crust, see Elements, abundance in earth s crust Acetaldehyde structure, 332 Acetamide, 338 Acetanilide, 344 Acetic acid in biochemistry, 428 structure, 333 Acetone... 

---