Potassium. .. Element

POTASSIUM. [CAS 7440-09-7]. Chemical element, symbol K, at, no. 19, at. wt. 39.098, periodic table group 1 (alkali metals i, mp 63,3cC, bp 760°C. density 0.86 g/cm3 (20°C). Elemental potassium has a body-centered cubic crystal structure. Potassium is a silver-white metal, can be readily molded, and cut by a knife, oxidizes instantly on exposure to air, and reacts violently with H2O, yielding potassium hydroxide and hydrogen gas, which burns spontaneously in air with a violet flame due to volatilized potassium element, is preserved under kerosene, burns in air at a red heat with a violet flame. Discovered by Davy in 1807. 

Mendeleev was convinced that he had discovered what he called the Periodic Law. The principle of the law was that the characteristics of the elements would vary periodically (that is, repeat at set intervals) as atomic weight went up. Characteristics such as specific density, oxidation states, and affinity (degree of chemical interactions) would vary for each element, but such variation was within a specific range that was common to a particular group. Thus, calcium (element 20) might be much heavier than magnesium (element 12) and only a bit heavier than potassium (element 19), but calcium and magnesium were related by chemical behavior. 

The third fundamental particle, the neutron, eluded discovery until 1932. James Chadwick (1891-1974) correctly interpreted experiments on the bombardment of beryllium with high-energy a-particles. Later experiments showed that nearly all elements up to potassium, element 19, produce neutrons when they are bombarded with high-energy a-particles. The neutron is an uncharged particle with a mass slightly greater than that of the proton. 

Lithium, sodium, and potassium, elements of the leftmost column of the periodic table (Group lA), have a single electron in their outermost s orbital (wr ). Beryllium and magnesium, of Group HA, have two electrons in their outermost shell, ns, while boron and aluminum (Group IHA) have three electrons in their outermost shell, rn np. Similar observations can be made for other A group elements. 

Potassium, element number 19, has a density of 0.86 g/cm3 and is so soft that it can be cut with a butter knife. It is even more reactive with water and oxygen than lithium or sodium are, so that potassium also is never found as the pure metal. In addition, for safety reasons, it is rarely handled as the pure metal. In part for safety reasons, there is little demand in industry for potassium metal itself except to make sodium-potassium alloys. 

The addition of silica fume to this geo-material has involved modifications in terms of chemistry and in the porosity of the sample. The synthesized inorganic foam was characteristic of a porous material where the size can be controlled by drying and by the chemistry, notably the molar ratio of Si/AI and Si/K. This demonstrates the importance of the potassium element. Furthermore, this in-situ inorganic foam is characteristic of an insulating material. 

CH2CI-CO-CH3. Colourless lachrymatory liquid b.p. 119°C. Manufactured by treating propanone with bleaching powder or chlorine. It is used as a tear gas and is usually mixed with the more potent bromoacetone. chloro acids Complex chloroanions are formed by most elements of the periodic table by solution of oxides or chlorides in concentrated hydrochloric acid. Potassium salts are precipitated from solution when potassium chloride is added to a solution of the chloro acid, the free acids are generally unstable. 

The table contains vertical groups of elements each member of a group having the same number of electrons in the outermost quantum level. For example, the element immediately before each noble gas, with seven electrons in the outermost quantum level, is always a halogen. The element immediately following a noble gas, with one electron in a new quantum level, is an alkali metal (lithium, sodium, potassium, rubidium, caesium, francium). 

L. silex, silicis, flint) Davy in 1800 thought silica to be a compound and not an element later in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride. 

It is recovered commercially from monazite sand, which contains about 3%, and from bastnasite, which contains about 0.2%. Wohler obtained the impure element in 1828 by reduction of the anhydrous chloride with potassium. The metal is now produced commercially by reduction of the fluoride with calcium metal. It can also be prepared by other techniques. 

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. 

Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere. 

Ultrapure iodine can be obtained from the reaction of potassium iodide with copper sulfate. Several other methods of isolating the element are known. 

Iodine compounds are important in organic chemistry and very useful in medicine. Iodides, and thyroxine which contains iodine, are used internally in medicine, and as a solution of KI and iodine in alcohol is used for external wounds. Potassium iodide finds use in photography. The deep blue color with starch solution is characteristic of the free element. 

Separation of tantalum from niobium requires several complicated steps. Several methods are used to commercially produce the element, including electrolysis of molten potassium fluorotantalate, reduction of potassium fluorotantalate with sodium, or reacting tantalum carbide with tantalum oxide. Twenty five isotopes of tantalum are known to exist. Natural tantalum contains two isotopes. 

The element was first prepared by Klemm and bonner in 1937 by reducing ytterbium trichloride with potassium. Their metal was mixed, however, with KCl. Daane, Dennison, and Spedding prepared a much purer from in 1953 from which the chemical and physical properties of the element could be determined. 

The Elements Lithium (Li), Sodium (Na), and Potassium (K) all formed oxides in the ratio of two atoms per oxygen atom R2O... 

The element potassium occurs naturally as " K, and "K. Of these, the is most abundant and " K is radioactive. The decay of " K follows two paths, one giving Ar and the other "Ca, as shown below. 

Some of the principal forms in which sulfur is intentionally incorporated in fertilizers are as sulfates of calcium, ammonium, potassium, magnesium, and as elemental sulfur. Ammonium sulfate [7783-20-2] normal superphosphate, and sulfuric acid frequendy are incorporated in ammoniation granulation processes. Ammonium phosphate—sulfate is an excellent sulfur-containing fertilizer, and its production seems likely to grow. Some common grades of this product are 12—48—0—5S, 12—12S, and 8—32—8—6.5S. 

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