Metals are chemical elements which have special differences from other elements, nonmetals. For example, metals have higher electric conductance unlike dielectrics and semiconductors. Also they have good heat conductivity. Except for mercury, all metals are solid substances in ordinary conditions. Receive metals in various ways, some of them can use.

Alkaline metal sodium was discovered in 1807 by the English chemist H. Davy in the course of electrolysis of caustic soda. In 1808 also managed to receive this metal Zh. Gay Lyusak and L. Tenar at decomposition of a caustic natr the heated iron.

Water always contains some quantity H^+ hydrogen ions and hydroxyl ions ОН^-. If it is more ions of hydrogen, water gains acid character if the hydroxyl ions, then alkaline is more. For assessment of degree of acidity of water solution there is a pH value. It is in number equal to a negative decimal logarithm of activity of hydrogen ions, unit of its dimension – mol/litre. That is rn = - lg [H^+]. Size rn fluctuates from 0 to 14. If it less than 7, solution sour. Respectively, if more than 7 – alkaline.

Got acquainted with iron of people at a civilization dawn. Its properties are rather well studied. However scientists still disagree on whether the smell has iron. Some researchers believe: no, has no. The smell, characteristic of iron, actually proceeds from skin of the person after its contact with this metal.