Alkali metals

Alkali metals - francium, cesium, rubidium, potassium, sodium, lithium - are called so because they form alkalis when interacting with water. Due to the 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, exhibit oxidation (single) +1 in the compounds. With an increase in the atomic mass of alkali metals, the reducing ability also increases. Virtually 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 hydrides. The products of combustion, as a rule, are peroxides.

Alkaline metal oxides are the solids of yellow (rubidium and potassium oxides), white (oxides of sodium and lithium), and orange (cesium oxide) colors. These oxides are able to react with water, acids, oxygen, acidic and amphoteric oxides. These basic properties are inherent in all of them and have a pronounced character.

Peroxides of alkaline metals are yellowish-white powders. They are able to react with carbon dioxide and carbon monoxide, acids, non-metals, water.

Hydroxides of alkaline metals are soluble in water solids of white color. In these compounds, the basic properties of alkalis (rather brightly) are manifested. From lithium to France, the strength of the bases and the degree of solubility in water increase. Hydroxides are considered to be sufficiently strong electrolytes. They react with salts, amphoteric hydroxides and oxides, individual non-metals, acid oxides. Except for the connection with lithium, all others exhibit thermal stability. When calcination of lithium hydroxide , its decomposition into water and oxide occurs. These compounds are obtained by electrolysis of chloride aqueous solutions, a number of exchange reactions. Hydroxides are also produced by the interaction of elements (or oxides) with water.

Virtually all the salts of the metals described (with the exception of individual lithium salts) in water are soluble well. Formed by weak acids, salt solutions have a medium (alkaline) reaction in connection with hydrolysis, but the salts formed by strong acids do not hydrolyze. Common salts are rock salt, silicate glue (soluble glass), potassium nitrate, bertholets salt, potassium permanganate, potassium soda, soda ash and others.

All alkali metal compounds have the ability to change the color of the flame. This is used in chemical analysis. Thus, the flame in the carmine-red color is stained by lithium ions, in violet - by ions of potassium, in yellow - by sodium, by whitish-pink - by rubidium, by violet-red - by cesium.

In connection with the fact that all the alkali elements are the most powerful reducing agents, they can be obtained by electrolysis of salt melts.

Application of alkali metals

Elements are used in different spheres of human activity. For example, cesium is used in photocells. In bearing alloys, lithium is used as the catalyst. Sodium is present in gas-discharge lamps, nuclear reactors as a coolant. Rubidium is used in research activities.