Chrome represents the 24th chemical element of the periodic table with alphabetic reference of "Cr" and with an atomic mass of 51.9961 g/mol. It treats type of solid metals or ferrous metals, and as well as at all elements, chrome has chemical and physical properties.
Instruction
1. So from physical properties of this metal it is possible to call its bluish-white color and also a cubic body-centered lattice. Temperature of transition of chrome from a paramagnetic state in anti-ferromagnetic (or achievement of a so-called point of Neel) – 39 degrees Celsius. This element is also ranked as group of the most solid pure metals with an indicator 5 on Moos's scale (one of the accepted criteria of hardness) on which chrome concedes only to following "Trinity" - tungsten, uranium and beryllium. In case of stay in very clean form the element perfectly gives in to mechanical influence and processing.
2. It is considered to be that four oxidation levels - +2, +3, +4 and +6 are characteristic of chrome. The first represents black SrO oxide with yellow hydroxide, is very strong reducer, the second – Cr2O3 – has green color and gray-green hydroxide, the third – CrO2 – is colourless, the malokharakterna also very seldom meets, and the last, the fourth – CrO3 – has red color, acid character and is the strongest oxidizer, hygroscopic and very poisonous.
3. Chrome is quite steady in interaction with air due to passivating (process of transition of a surface of metal to an inactive or passive state). For this reason it does not react with sulfuric and nitric acids. Chrome burns down at a temperature of 2000 degrees Celsius then green oxide with formula Cr2O3 and amphoteric properties is formed.
4. Modern chemists can synthesize compound of chrome and a pine forest (various borides – Cr2B, CrB, Cr3B4 and others), chrome and carbon (three types of carbides), chrome and silicon (three silicides) and is lame with nitrogen (two nitrides).
5. This chemical element is biogenous and constantly being a part of vegetable and animal fabrics. At animals chrome takes part in exchange of lipids, proteins and carbons, and its decrease in food and blood is capable to lead to reduction of growth rate and also increase in concentration of cholesterol in blood. In pure form it is quite toxic, and metal chromic dust is capable to cause the strongest irritation of pulmonary fabrics. Compounds of metal can also provoke dermatitis, lead to many diseases (including oncological character). Chrome is very spread in the nature surrounding the person, his main connections – chromite or so-called chromic iron ore with formula FeO Cr2O3 and krokoit PbCrO4.