Lithium (Lithium, Li) is a chemical element of the first group of the periodic system of elements of D. I. Mendeleyev. Ever since. number 3, atomic weight (mass) 6,939, valence +1. It is known 2 stable and 3 of the radioactive isotope. Lithium is included in the composition of plant and animal organisms. A person found in the lungs, liver, spleen, kidneys, blood (mostly in plasma). Lithium - soft, silver alkaline metal, density 0,534, temperature PL 180 degrees. Lithium is extremely reactive, air ignites (store L. in paraffin oil), with water forms alkali LiOH. Most salts L. soluble in water. Volatile compounds L. paint flames in Carmine-red color. Apply L. in alloys with other metals, glass, plastics and other Salt L. (benzoate, citrate, chloride) are used in medicine. In the body lithium is an antagonist of sodium. Connection L. introduced in amounts exceeding the physiological concentrations affect carbohydrate metabolism and tissue respiration. With long-term administration of high doses observed lithium poisoning: weakness, dizziness, the defeat of the gastrointestinal tract, slowing down the heart. Treatment - saline infusion, glucose, diuretics and laxatives.