Element in the earth’s crust

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... 

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. 

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. 

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... 

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 ... 

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. 

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... 

Aluminum is the most abundant metallic element in the Earth s crust and, after oxygen and silicon, the third most abundant element (see Fig. 14.1). However, the aluminum content in most minerals is low, and the commercial source of aluminum, bauxite, is a hydrated, impure oxide, Al203-xH20, where x can range from 1 to 3. Bauxite ore, which is red from the iron oxides that it contains (Fig. 14.23), is processed to obtain alumina, A1203, in the Bayer process. In this process, the ore is first treated with aqueous sodium hydroxide, which dissolves the amphoteric alumina as the aluminate ion, Al(OH)4 (aq). Carbon dioxide is then bubbled through the solution to remove OH ions as HCO and to convert some of the aluminate ions into aluminum hydroxide, which precipitates. The aluminum hydroxide is removed and dehydrated to the oxide by heating to 1200°C. 

Silicon is the second most abundant element in the Earth s crust. It occurs widely in rocks as silicates, compounds containing the silicate ion, Si032, and as the silica, Si02, of sand (Fig. 14.33). Pure silicon is obtained from quartzite, a granular form of quartz (another solid phase of SiOz), bv reduction with high-purity carbon in an electric arc furnace ... 

As a result of its unique chemical and physical properties, silica gel is probably the most important single substance involved in liquid chromatography today. Without silica gel, it is doubtful whether HPLC could have evolved at all. Silica gel is an amorphous, highly porous, partially hydrated form of silica which is a substance made from the two most abundant elements in the earth s crust, silicon and oxygen. Silica, from which silica gel is manufactured, occurs naturally, either in conjunction with metal oxides in the form of silicates, such as clay or shale, or as free silica in the form of quartz, cristobalite or tridymite crystals. Quartz is sometimes found clear and colorless, but more often in an opaque form, frequently colored... 

The natural occurrence of the group-IIA elements ranges from common to rare e.g., Ca is 5th in the order of atomic abundance of the elements in the earth s crust. Mg is 7th, Ba and Sr are 21st and 22nd, respectively, and Be is 32nd . Radium is of extremely limited availability. It does occur naturally, although it has neither stable nor long-lived radioaetive isotopes it is found in association with U, since ll/2... 

Silicon is one of the most abundant elements in the earth s crust. We find silicon in sand and quartz, and in our NMR tubes. Of course we also find it in the computers which run our NMR spectrometers. 

Cobalt is the 30th element in the earth s crust with an average of 20-30 mg/kg (Bowen, 1979 Vinogradov, 1959). Ultrabasic rocks and their metamorphized serpentines contain 100-200 mg/kg Co, followed by basic igneous rocks (30-45 mg/kg), while acid rocks have the lowest Co... 

Table 2.1. Concentrations of trace elements in the earth s crust, rocks, and world soils ... 

Zinc is the 24th most abundant element in the earth s crust. The Zn concentration in the lithosphere is 50-70 mg/kg (Vinogradoc, 1959 Adriano, 2001). Basic igneous rocks contain higher Zn (70-130 mg/kg) than metamorphic and sedimentary rocks (80 mg/kg). Carbonate and limestones contain low Zn (16-20 mg/kg) (Aubert and Pinta, 1977). The total Zn concentration in the soils of the world ranges from 10 to 300 mg/kg (Swaine, 1955), with average concentrations from 50 to 100 mg/kg (Aubert and Pinta, 1977). Arid and semi-arid soils vary from trace levels (subdesert soils) to 900 mg/kg (saline alkali soils) (Aubert and Pinta, 1977). The average Zn concentration in the arid and semi-arid soils of the U.S. (62.9 mg/kg) is... 

Global extent of arid and semi-arid soils (km2) based on the Soil Taxonomy system) (after Monger et al., 2004). Concentrations of trace elements in the earth s crust, rocks and world soils3. 

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