Elemental steel gray metal. The element name comes from the Greek word, meaning "color", because the chromium compounds have color. In 1797 the French chemist Wo Kelan (L.N.Vauquelin) found a new mineral in the Siberian red lead (chrome lead), the next year with carbon reduction. Chromium in the crust in the content of 0.01%, ranking the first 17. There is no free state of chromium in nature, mainly in the chrome lead [1]. In the periodic table of the group VIB, the atomic number of chromium 24, the atomic weight of 51.9961, body-centered cubic crystals, the common valence of +2, +3 and +6. The oxidation number is 6, 5, 4, 3, 2, 1, -1, -2, -4 [2], is the hardness of the largest metal.
