Sodium elemental abundances

Sodium, element number 11, is a soft and silvery gray metal with a density of 0.97 g/cm3. Since this value is less than the density of water, sodium metal floats (although it reacts violently with the water upon contact). Sodium is so soft that it can be cut and shaped with a butter knife. It is the most abundant of the alkali metals, readily obtained from seawater, and used in a large number of applications. Of all the alkali metals, sodium metal is the one produced and used in industry in greatest quantity. 

Kieffer (1991) cites 37 chemical species as usually present in the elemental composition of the human body. Among them there are elements abundant in nature, such as calcium, sodium and potassium, as well as rather rare ones, such as iodine and cobalt. 

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. 

Potassium and sodium share the position of the seventh most abundant element on earth. Common minerals such as alums, feldspars, and micas are rich in potassium. Potassium metal, a powerful reducing agent, does not exist in nature. 

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. 

Sodium, 22 700 ppm (2.27%) is the seventh most abundant element in crustal rocks and the fifth most abundant metal, after Al, Fe, Ca and Mg. Potassium (18 400 ppm) is the next most abundant element after sodium. Vast deposits of both Na and K salts occur in relatively pure form on all continents as a result of evaporation of ancient seas, and this process still continues today in the Great Salt Lake (Utah), the Dead Sea and elsewhere. Sodium occurs as rock-salt (NaCl) and as the carbonate (trona), nitrate (saltpetre), sulfate (mirabilite), borate (borax, kemite), etc. Potassium occurs principally as the simple chloride (sylvite), as the double chloride KCl.MgCl2.6H2O (camallite) and the anhydrous sulfate K2Mg2(S04)3 (langbeinite). There are also unlimited supplies of NaCl in natural brines and oceanic waters ( 30kgm ). Thus, it has been calculated that rock-salt equivalent to the NaCl in the oceans of the world would occupy... 

Sodium (fifth most abundant element) is found principally as Na+ ion in water soluble salt deposits, such as NaCl, and in salt waters. The element reacts rapidly with water and with atmospheric oxygen, hence is not found in an uncombined state in nature. 

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. 

The elements occur in widely varying quantities on earth. The 10 most abundant elements make up 98% of the mass of the crust of the earth. Many elements occur only in traces, and a few are synthetic. Fortunately for humanity, the elements are not distributed uniformly throughout the earth. The distinct properties of the different elements cause them to be concentrated more or less, making them more available as raw materials. For example, sodium and chlorine form salt, which is concentrated in beds by being dissolved in bodies of water which later dry up. Other natural processes are responsible for the distribution of the elements which now exist on earth. It is interesting to note that the different conditions on the moon—for example, the lack of water and air on the surface—might well cause a different sort of distribution of the elements on the earth s satellite. 

The moon rocks brought back to earth are only a tiny sample of the moon s surface, but they are enough to show that some elements common on earth may be rare on the moon, and some that are rare here on earth may be common on the moon. So far, as on earth, oxygen and silicon seem to be the most common lunar elements. Early experiments have found more uranium and less potassium, more titanium and less sodium. Oxygen is strikingly absent from some minerals, but natural glass is far more common than it is on earth. The rare, noble gases are fairly abundant, trapped in little bubbles in the rocks. 

Although boron ranks 48th among the elements in abundance, it is not found uncombined. The most common minerals containing boron are the tetraborates of sodium or calcium. Borax, Na2B407 10H2O, is the most important source of boron, and large deposits of borax are found in southern California, from which about three-fourths of the world demand is obtained. 

The ash of peat forming plant species contains a predominant amount of silicon. This element is particularly abundant in the Sphagnum, where its content achieves 36% by ash weight. Iron and aluminum are the next abundant. The first is accumulated during the peat formation process. The accumulation of calcium and potash is more pronounced than sodium, and the sulfur content is also remarkable. A large amount of mechanically admixed mineral particles (40-80% by ash weight) is found in mosses. This is due to the deposition of fine dispersed mineral material from snowmelting waters and atmosphere dust deposition (Table 1). 

Sodium is the sixth most abundant of the Earths elements. Since it is a highly electropositive metal and so reactive with nonmetals, it is not found in its pure elemental form on Earth. Rather, it is found in numerous compounds in relatively abundant quantities. About 2.83% of the Earths crust consists of sodium in compounds. 

Sodium is produced by an electrolytic process, similar to the other alkali earth metals. (See figure 4.1). The difference is the electrolyte, which is molten sodium chloride (NaCl, common table salt). A high temperature is required to melt the salt, allowing the sodium cations to collect at the cathode as liquid metallic sodium, while the chlorine anions are liberated as chlorine gas at the anode 2NaCl (salt) + electrolysis —> Cl T (gas) + 2Na (sodium metal). The commercial electrolytic process is referred to as a Downs cell, and at temperatures over 800°C, the liquid sodium metal is drained off as it is produced at the cathode. After chlorine, sodium is the most abundant element found in solution in seawater. 

Because sodium is such a reactive element and is not found in its elemental form, it is responsible for the formation of many compounds on the Earth s surface. Sodium oxide (Na O), also known as sodium monoxide, is the most abundant and caustic salt of sodium in the Earth s crust, but sodium chloride (NaCl) is probably the most common and useful. Other... 

Potassium is the eighth most abundant element in the Earths crust, which contains about 2.6% potassium, but not in natural elemental form. Potassium is slightly less abundant than sodium. It is found in almost all solids on Earth, in soil, and in seawater, which contains 380 ppm of potassium in solution. Some of the potassium ores are sylvite, carnallite, and polyha-lite. Ore deposits are found in New Mexico, California, Salt Lake in Utah, Germany, Russia, and Israel. Potassium metal is produced commercially by two processes. One is thermochemical distillation, which uses hot vapors of gaseous NaCl (sodium chloride) and KCl (potassium chloride) the potassium is cooled and drained off as molten potassium, and the sodium chloride is discharged as a slag. The other procedure is an electrolytic process similar to that used to produce hthium and sodium, with the exception that molten potassium chloride (which melts at about 770°C) is used to produce potassium metal at the cathode (see figure 4.1). 

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