Alkaline metals - France, cesium, rubidium, potassium, sodium, lithium - are called so because they form alkalis when interacting with water. Due to their high ability to react, these elements should be stored under a layer of mineral oil or kerosene. The most active of all these substances is considered to be France (has radioactivity).
Alkali metals are soft, silvery substances. Their freshly cut surface has a characteristic luster. Alkali metals boil and melt at low temperatures, have high heat and electrical conductivity. They also have a low density.
Chemical properties of alkali metals
Substances are strong reducing agents; they exhibit an oxidation state (single) of +1 in compounds. With an increase in the atomic mass of alkali metals, the reduction ability also increases. Almost all compounds are soluble in water, all of them are ionic in nature.
With moderate heating, alkali metals ignite in air. In conjunction with hydrogen, substances form salt-like hydrides. The products of combustion, as a rule, are peroxides.
Alkali metal oxides are solids of yellow (oxides of rubidium and potassium), white (oxides of sodium and lithium), and orange (cesium oxide) colors. These oxides are capable of reacting with water, acids, oxygen, acidic and amphoteric oxides. These basic properties are inherent in all of them and are pronounced.
Alkali metal peroxides are yellowish-white powders. They are able to react with carbon dioxide and carbon monoxide, acids, non-metals, water.
Hydroxides of alkali metals are white soluble solids in white. In these compounds, the basic properties of alkalis manifest themselves (quite brightly). From lithium to France, the strength of the bases and the degree of solubility in water are increasing. Hydroxides are considered quite strong electrolytes. They react with salts, amphoteric hydroxides and oxides, individual non-metals, acid oxides. With the exception of lithium, all others exhibit thermal stability. When calcining lithium hydroxide , it decomposes into water and oxide. These compounds are obtained by electrolysis of chloride aqueous solutions, a number of metabolic reactions. Hydroxides are also obtained by the interaction of elements (or oxides) with water.
Almost all salts of the described metals (with the exception of individual lithium salts) are well soluble in water. Formed by weak acids, salt solutions have a medium reaction (alkaline) due to hydrolysis, while salts formed by strong acids do not hydrolyze. Common salts are rock (table) salt, silicate glue (soluble glass), potassium nitrate, bertoletova salt, potassium permanganate, drinking soda, soda ash and others.
All alkali metal compounds have the ability to change the color of the flame. It is used in chemical analysis. So, a carmine-red flame is colored with lithium ions, violet with potassium ions, yellow with sodium, whitish pink with rubidium, and violet red with cesium.
Due to the fact that all alkaline elements are the most powerful reducing agents, they can be obtained by electrolysis of molten salts.
The use of alkali metals
Elements are used in various fields of human activity. For example, cesium is used in solar cells. In bearing alloys, lithium is used as a catalyst. Sodium is present in gas discharge lamps, nuclear reactors as a coolant. In research activities, rubidium is used.