Iron is a metal element with atomic number 26 and its chemical formula is Fe. Pure iron is white or silvery white with metallic luster. Melting point 1538℃, boiling point 2750℃, soluble in strong acid and medium acid, insoluble in water. Iron has zero, +2, +3 and +6 valence, of which +2 and +3 valence are common and +6 valence is rare.
Extended data:
I. Chemical properties
Iron is an indispensable metal in the industrial sector. Iron and a small amount of carbon make up an alloy steel, which is not easy to demagnetize after magnetization. It is an excellent hard magnetic material, an important industrial material and the main raw material of artificial magnetism. Iron has many allotropes.
Iron is a relatively active metal, which ranks ahead of hydrogen in the metal activity sequence table. Its chemical properties are active and it is a good reducing agent. Iron can't burn in air, but it can burn violently in oxygen.
At room temperature, iron is not easy to react with oxygen, sulfur, chlorine and other nonmetallic simple substances in dry air, and it is easy to rust if there are impurities in humid air; Rust is faster in humid air containing acid, alkali or salt solution.
The reaction is intense at high temperature, such as iron burning in oxygen to produce Fe? o？ Red-hot iron reacts with water vapor to produce Fe? o？ . It can be combined with halogen, sulfur, silicon, carbon and phosphorus when heated. In addition to the formation of +2 and +3 valence oxides, there are also complex oxides Fe? o？ (the main component of a magnet).
Iron is easily soluble in dilute inorganic acids, forming ferrous salts and releasing hydrogen. When it meets concentrated sulfuric acid or concentrated nitric acid at room temperature, an oxide protective film is formed on the surface to "passivate" iron, so iron products can be used to hold cold concentrated sulfuric acid or cold concentrated nitric acid. When heated, iron can react with concentrated sulfuric acid or concentrated nitric acid to form +3 valence iron salt, so? Still not? .
Second, the use
1, used in pharmacy, pesticide, powder metallurgy, hot hydrogen generator, gel propellant, combustion activator, catalyst, water purification adsorbent, sintering activator, powder metallurgy products, various mechanical parts products, cemented carbide materials products, etc.
2. Pure iron is used to manufacture iron cores of generators and motors, reduced iron powder is used in powder metallurgy, and steel is used to manufacture machines and tools. In addition, iron and its compounds are also used to make magnets, medicines, inks, pigments, abrasives and so on.
3. Used as reducing agent. Used for preparing iron salts. But also can be used for preparing electronic components.
4, used as a nutritional supplement (iron fortifier).
Baidu encyclopedia-iron