Chromium chloride hydrate series#

Chromium chloride hydrate series#

(Similar promotions happen for every transition metal atom but one, palladium.) Ĭhromium is the first element in the 3d series where the 3d electrons start to sink into the nucleus they thus contribute less to metallic bonding, and hence the melting and boiling points and the enthalpy of atomisation of chromium are lower than those of the preceding element vanadium. This lowers the energetic cost of promotion and increases the energy released by it, so that the promotion becomes energetically feasible and one or even two electrons are always promoted to the 4s subshell. However, in the 3d transition metals, the energy gap between the 3d and the next-higher 4s subshell is very small, and because the 3d subshell is more compact than the 4s subshell, inter-electron repulsion is smaller between 4s electrons than between 3d electrons. In the previous elements, the energetic cost of promoting an electron to the next higher energy level is too great to compensate for that released by lessening inter-electronic repulsion. This occurs because electrons in the same orbital repel each other due to their like charges. This occurs again later in the periodic table with other elements and their electron configurations, such as copper, niobium, and molybdenum. It is also the first element in the periodic table whose ground-state electron configuration violates the Aufbau principle. Physical properties Atomic Ĭhromium is the fourth transition metal found on the periodic table, and has an electron configuration of 3d 5 4s 1. Ībandoned chromium production sites often require environmental cleanup. According to the European Chemicals Agency (ECHA), chromium trioxide that is used in industrial electroplating processes is a 'substance of very high concern' (SVHC). While chromium metal and Cr(III) ions are considered non-toxic, hexavalent chromium, Cr(VI), is toxic and carcinogenic. However, in 2014, the European Food Safety Authority, acting for the European Union, concluded that there was insufficient evidence for chromium to be recognized as essential. In the United States, trivalent chromium (Cr(III)) ion is considered an essential nutrient in humans for insulin, sugar, and lipid metabolism. Pure chromium metal is produced by a different process: roasting and leaching of chromite to separate it from iron, followed by reduction with carbon and then aluminium. Ferrochromium is then used to produce alloys such as stainless steel. Industrial production of chromium proceeds from chromite ore (mostly FeCr 2O 4) to produce ferrochromium, an iron-chromium alloy, by means of aluminothermic or silicothermic reactions. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, because many chromium compounds are intensely colored. Polished chromium reflects almost 70% of the visible spectrum, and almost 90% of infrared light. Chromium is also greatly valued as a metal that is able to be highly polished while resisting tarnishing. Stainless steel and chrome plating ( electroplating with chromium) together comprise 85% of the commercial use. A major development in steel production was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Ĭhromium metal is valued for its high corrosion resistance and hardness. It is a steely-grey, lustrous, hard, and brittle transition metal. Chemical Class: The hexahydrate of chromium(3+) trichloride.Chromium is a chemical element with the symbol Cr and atomic number 24.OU Chemical Safety Data (No longer updated) More details Safety glasses, gloves, good ventilation.Treat as a possible carcinogen. Toxicity: ORL-RAT LD50 1790 mg kg-1, IPR-MUS LD50 520 mg kg-1 OU Chemical Safety Data (No longer updated) More details.Hygroscopic.Incompatible with lithium, nitrogen, strong oxidizing agents. Stability: Stable, but may be air-sensitive.Appearance: greenish-black to violet crystals OU Chemical Safety Data (No longer updated) More details.

Experimental Solubility: Slightly soluble in acetone.Experimental Melting Point: 83 ☌ Alfa AesarĨ3 ☌ OU Chemical Safety Data (No longer updated) More details.Experimental Physico-chemical Properties.