From Big Medical Encyclopedia

ALKALINE EARTH METALS — chemical elements of subgroup of IIA calcium of a periodic system of D. I. Mendeleyev. Treat alkaline earth metals calcium (see), strontium (see), barium (see), radium (see) and relatives on a number of properties beryllium (see) and magnesium (see). Calcium along with oxygen, carbon, hydrogen, nitrogen and phosphorus makes the ground mass of living material, possesses high biol. activity, is the main structural component of bones of a skeleton (see the Bone) and teeth (see Teeth) the person and animals, and also an important component of coagulant system of blood (see); in food of the person calcium is an irreplaceable element. One of the most important bio-elements — magnesium — with luzhit the activator of many enzymatic processes, is necessary for normal functioning of nervous and muscular tissue. Other treat microelements (see) Shch. m (except beryllium and radium). Contents nek-ry Shch. the m, especially calcium and magnesium, in blood, urine and other environments of an organism is informative diagnostic test at many diseases. Connections nek-ry Shch. m are used in medicine as pharmaceuticals.

The IIA elements of subgroup of the Periodic Table (see) received the name from the word «earths», the Crimea alchemists called oxides Shch. m and to-rye gave to water alkali reaction (see Alkalis).

Y. m have close physical and chemical properties (especially calcium, strontium and barium), in connections show valency + 2. Chemical activity Shch. the m increases among from calcium to radium. In usual conditions they react with oxygen (beryllium — during the heating to 800 ° above), water, fluorine and other halogens (see). With hydrogen Shch. m react at elevated temperatures, are dissolved in diluted mineral to-takh and liquid ammonia. Compounds of beryllium and barium (an exception — fixed white) are strongly poisonous.

On ability to form complex connections (see) Shch. m are intermediate between alkali metals (see) and transition metals. Ions shch. m form about a complex of an onama (see) rather steady complexes having great practical value. They are used also for quantitative definition Shch. m of Kompleksonata of calcium (those-tatsin calcium, etc.) apply to removal from an organism of lead, manganese and other metals.

Jonah Shch. the m which are present at blood and cellular liquids mostly are in a type of complex connections with proteins (see). Bibliography: Kotton F. A. and Wil

kinson J. Fundamentals of inorganic chemistry, the lane with English, M., 1979; H e to r the expert about in B. V. Fundamentals of the general chemistry, t. 2, M., 1969; Hughes M. Inorganic

chemistry of biological processes, the lane with English, M., 1983.

A. V. Babkov.