Potassium group 1 element

Nuphar lutea, a plant very sensitive to perturbations such as those which may accompany the mining of metal ores, was also examined in order to measure the content of radionuclides in a series of uranium group elements (11). In experiments carried out in the Okanagan region of south-central British Columbia, N. lutea was found to accumulate natural uranium and 226 Ra, and the amounts of these elements were found to depend on the season and also on the pH of the mud. Nuphar lutea was also used in investigations into the concentration of137Cs and potassium in Lake Ulkesjon in the southern part of Sweden (12). 

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. 

The transition metals, essential for humans and, also, several of those found as polluting metals, are present at considerably lower concentrations than the main group elements, sodium, potassium, calcium, etc. mentioned above and, therefore, contribute little to the isotonic pressure via their solvation properties. They do, however, have a fascinating and essential role which involves coordination complexes. In such reactions, they pair off with a ligand and become an essential part of a biochemical process. 

Metallurgy. — The metals of most of the cerium group elements have been prepared, three general methods having been used t (1) fusion of the anhydrous halides with sodium, potassium, calcium, or aluminium (2) electrolysis of the fused chlorides or of a solution of the oxide in the molten fluoride (3) heating the oxides with magnesium, calcium, or silicon. Reduction with aluminium has also been tried, but it is not satisfactory except possibly for cerium itself. Electrolysis has been the most successful, the other methods usually giving at best an alloy. 

The saltiness of the oceans was well known from ancient times and salt was used for domestic uses. But the major composition of sea water was yet to be determined. As early as 1820 William Wollaston, the discoverer of palladium and rhodium, predicted the presence of potassium in sea water and then proceeded to determine its concentration using gravimetric analytical techniques, based on the newly discovered platinum group elements and the formation of potassium-platinum compounds. 

Tellurium is less widely distributed in nature than selenium both elements belong to Group VI of the periodic table. When fused with potassium cyanide, elemental tellurium is converted into potassium telluride, K2Te, which dissolves in water to yield a red solution. If air is passed through the solution, the tellurium is precipitated as a black powder (difference and method of separation from selenium). Selenium under similar conditions yields the stable potassium selenocyanide, KSeCN the selenium may be precipitated by the addition of dilute hydrochloric acid to its aqueous solution. 

There were many different approaches to the task of grouping the elements. In 1817, Johann Wolfgang Ddbereiner (1780-1849) proposed one of the first systems to organize the mineral world. His idea was to group elements into triads of related substances. Later, he focused on triads composed of the elements themselves, for example, lithium, sodium, and potassium. He found that within the triads he identified, the intermediate atomic mass was close to the arithmetic mean of the atomic masses of the other two. Moreover, other properties such as density, melting point, and boiling point behaved similarly. 

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). 

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. 

Rubidium [7440-17-7] Rb, is an alkali metal, ie, ia Group 1 (lA) of the Periodic Table. Its chemical and physical properties generally He between those of potassium (qv) and cesium (see Cesiumand cesium compounds Potassium compounds). Rubidium is the sixteenth most prevalent element ia the earth s cmst (1). Despite its abundance, it is usually widely dispersed and not found as a principal constituent ia any mineral. Rather it is usually associated with cesium. Most mbidium is obtained from lepidoHte [1317-64-2] an ore containing 2—4% mbidium oxide [18088-11-4]. LepidoHte is found ia Zimbabwe and at Bernic Lake, Canada. 

Strontium [7440-24-6] Sr, is in Group 2 (IIA) of the Periodic Table, between calcium and barium. These three elements are called alkaline-earth metals because the chemical properties of the oxides fall between the hydroxides of alkaU metals, ie, sodium and potassium, and the oxides of earth metals, ie, magnesium, aluminum, and iron. Strontium was identified in the 1790s (1). The metal was first produced in 1808 in the form of a mercury amalgam. A few grams of the metal was produced in 1860—1861 by electrolysis of strontium chloride [10476-85-4]. 

---