Sierra Acai Company
Sierra Acai Company
Open 7 Days a Week
MonaVie Independent Distributor
Distributor Training
Shop Online
Enroll Now
Buy Wholesale and maintain an Active status for 2 months and we will refund your $39 Distributor Fee
Friends
Buy Wholesale and maintain an Active status for 2 months and we will refund your $39 Distributor Fee
10-SEPTEMBER-2008 16:47:15 - Chromium 24 vanadium â†? chromium → manganese - ↑ Cr ↓ Mo Chromium in the periodic table of the elements Periodic table - Extended periodic table General Name, symbol, number chromium, Cr, 24 Chemical series transition metals Group, period, block 6, 4, d Appearance silvery metallic Standard atomic weight 51.99616 g·mol-1 Electron configuration Ar 3d5 4s1 Electrons per shell 2, 8, 13, 1 Physical properties Phase solid Density near r.t. 7.19 g·cm-3 Liquid density at m.p. 6.3 g·cm-3 Melting point 2180 K 1907 °C, 3465 °F Boiling point 2944 K 2671 °C, 4840 °F Heat of fusion 21.0 kJ·mol-1 Heat of vaporization 339.5 kJ·mol-1 Specific heat capacity 25 °C 23.35 J·mol-1·K-1 Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 1656 1807 1991 2223 2530 2942 Atomic properties Crystal structure cubic body centered Oxidation states 6, 5 2, 4, 3, 2, 1 strongly acidic oxide Electronegativity 1.66 Pauling scale Ionization energies more 1st: 652.9 kJ·mol-1 2nd: 1590.6 kJ·mol-1 3rd: 2987 kJ·mol-1 Atomic radius 140 pm Atomic radius calc. 166 pm Covalent radius 127 pm Miscellaneous Magnetic ordering AFM rather: SDW Electrical resistivity 20 °C 125 nΩ·m Thermal conductivity 300 K 93.9 W·m-1·K-1 Thermal expansion 25 °C 4.9 µm·m-1·K-1 Speed of sound thin rod 20 °C 5940 m/s Young's modulus 279 GPa Shear modulus 115 GPa Bulk modulus 160 GPa Poisson ratio 0.21 Mohs hardness 8.5 Vickers hardness 1060 MPa Brinell hardness 1120 MPa CAS registry number 7440-47-3 Selected isotopes Main article: Isotopes of chromium iso NA half-life DM DE MeV DP 50Cr 4.345% 1.8×1017y εε - 50Ti 51Cr syn 27.7025 d ε - 51V γ 0.320 - 52Cr 83.789% 52Cr is stable with 28 neutrons 53Cr 9.501% 53Cr is stable with 29 neutrons 54Cr 2.365% 54Cr is stable with 30 neutrons References This box: view talk Chromium pronounced /ˈkroÊŠmiÉ™m/ is a chemical element which has the symbol Cr and atomic number 24. It is a steel-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odourless, tasteless, and malleable. Chromium was named after the Greek word ChrÅ?ma χÏ?ωμα meaning color, because of the many colorful compounds made from it.1 Contents 1 History 2 Occurrence and production 3 Chemical properties 4 Compounds 4.1 Chromium and the quintuple bond 5 Applications 6 Biological role 7 Isotopes 8 Precautions 9 See also 10 References 11 External links History Chromium's history dates back thousands of years. Weapons found in burial pits dating from the late 3rd century BC Qin Dynasty of the Terracotta Army near Xi'an, China have been analyzed by archaeologists. Although more than 2,000 years, the ancient bronze tips of crossbow bolts and swords found at the site showed no sign of corrosion, the reason being that the Qin era Chinese had coated the bronze in chromium.2 Chromium did not come to the attention of westerners until the 18th century. On 26 July 1761, Johann Gottlob Lehmann found an orange-red mineral in the Ural Mountains which he named Siberian red lead. Though misidentified as a lead compound with selenium and iron components, the material was in fact lead chromate with a formula of PbCrO4, now known as the mineral crocoite. In 1770, Peter Simon Pallas visited the same site as Lehmann and found a red lead mineral that had very useful properties as a pigment in paints. The use of Siberian red lead as a paint pigment developed rapidly. A bright yellow made from crocoite also became fashionable. In 1797, Louis Nicolas Vauquelin received samples of crocoite ore. He was able to produce chromium oxide with a chemical formula of CrO3, by mixing crocoite with hydrochloric acid. In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven. He was also able to detect traces of chromium in precious gemstones, such as ruby, or emerald. Later that year he successfully isolated elemental chromium. During the 1800s chromium was primarily used as a component of paints and in tanning salts but now metal alloys account for 85% of the use of chromium. The remainder is used in the chemical industry and refractory and foundry industries. Occurrence and production World production trend World production trend Chromium is mined as chromite FeCr2O4 ore. About two-fifths of the chromite ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia, and Turkey are also substantial producers. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan and southern Africa. Approximately 15 million tons of marketable chromite ore were produced in 2000, and converted into approximately 4 million tons of ferro-chrome with an approximate market value of 2.5 billion United States dollars. Though native chromium deposits are rare, some native chromium metal has been discovered. The Udachnaya Mine in Russia produces samples of the native metal. This mine is a kimberlite pipe rich in diamonds, and the reducing environment so provided helped produce both elemental chromium and diamond. See also chromium minerals Chromium is obtained commercially by heating the ore in the presence of aluminium or silicon. Chemical properties Chromium Chromium Chromium is a member of the transition metals, in group 6. Chromium0 has an electronic configuration of 4s13d5, due to the lower energy of the high spin configuration. Chromium exhibits a wide range of possible oxidation states. The most common oxidation states of chromium are +2, +3, and +6, with +3 being the most stable. +1, +4 and +5 are rare. Chromium compounds of oxidation state +6 are powerful oxidants. Chromium is passivated by oxygen, forming a thin usually a few atoms thick being transparent because of thickness protective oxide surface layer with another element such as nickel, and/or iron. It forms a compound called a spinel structure which, being very dense, prevents diffusion of oxygen into the underlying layer. In iron or plain carbon steels the oxygen actually migrates into the underlying material. Chromium is usually plated on top of a nickel layer which may or may not have been copper plated first. Chromium, unlike other metals such as iron and nickel, does not suffer from hydrogen embrittlement. It does though suffer from nitrogen embrittlement and hence no straight chromium alloy has ever been developed. Below the pourbaix diagram can be seen, it is important to understand that the diagram only displays the thermodynamic data and it does not display any details of the rates of reaction. The Pourbaix diagram for chromium in pure water, perchloric acid or sodium hydroxide The Pourbaix diagram for chromium in pure water, perchloric acid or sodium hydroxide3 Compounds Main article: Chromium compounds Potassium dichromate is a powerful oxidizing agent and is the preferred compound for cleaning laboratory glassware of any trace organics. It is used as a saturated solution in concentrated sulfuric acid for washing the apparatus. For this purpose, however, sodium dichromate is sometimes used because of its higher solubility 5 g/100 ml vs. 20 g/100 ml respectively. Chrome green is the green oxide of chromium, Cr2O3, used in enamel painting, and glass staining. Chrome yellow is a brilliant yellow pigment, PbCrO4, used by painters. Chromic acid has the hypothetical structure H2CrO4. Neither chromic nor dichromic acid is found in nature, but their anions are found in a variety of compounds. Chromium trioxide, CrO3, the acid anhydride of chromic acid, is sold industrially as chromic acid. Chromium and the quintuple bond The compound synthesized by Nguyen, which was determined experimentally to contain a Cr-Cr quintuple bond The compound synthesized by Nguyen, which was determined experimentally to contain a Cr-Cr quintuple bond Chromium is notable for its ability to form quintuple covalent bonds. The synthesis of a compound of chromiumI and a hydrocarbon radical was shown via X-ray diffraction to contain a quintuple bond of length 183.514 pm 1.835 angstroms joining the two central chromium atoms.4 This was accomplished through the use of an extremely bulky monodentate ligand which through its sheer size prevents further coordination. Chromium currently remains the only element for which quintuple bonds have been observed. Applications Uses of chromium: In metallurgy, to impart corrosion resistance, create a shiny finish, or increase hardness: as an alloy constituent, such as in stainless steel in chrome plating chromic acid is used in some anodizing processes As dyes and paints: ChromiumIII oxide is a metal polish known as green rouge. Chromium salts color glass an emerald green. Chromium is what makes a ruby red, and therefore is used in producing synthetic rubies. also makes a brilliant yellow for painting As a catalyst. Chromite is used to make molds for the firing of bricks. Chromium salts are used in the tanning of leather. Potassium dichromate is a chemical reagent, used in cleaning laboratory glassware and as a titrating agent. It is also used as a mordant i.e., a fixing agent for dyes in fabric. ChromiumIV oxide CrO2 is used to manufacture magnetic tape, where its higher coercivity than iron oxide tapes gives better performance. In well drilling muds as an anti-corrosive. In medicine, as a dietary supplement or slimming aid, usually as chromiumIII chloride, chromiumIII picolinate, chromiumIII polynicotinate or as an amino acid chelate, such as chromiumIII D-phenylalanine.5 Chromium hexacarbonyl CrCO6 is used as a gasoline additive. Chromium boride CrB is used as a high-temperature electrical conductor. ChromiumIII sulfate Cr2SO43 is used as a green pigment in paints, in ceramic, varnishes and inks as well as in chrome plating. ChromiumVI is used in the post Ballard preparation of Gravure rotogravure printing Forme Cylinders. By electroplating the metal onto the second coat of copper after the Ballard skin, the longevity of the printing cylinder is increased. Biological role Trivalent chromium CrIII, or Cr3+ is required in trace amounts for sugar metabolism in humans Glucose Tolerance Factor and its deficiency may cause a disease called chromium deficiency. In contrast, hexavalent chromium is very toxic and mutagenic when inhaled as publicized by the film Erin Brockovich. CrVI has not been established as a carcinogen when not inhaled but in solution it is well established as a cause of allergic contact dermatitis ACD.6 Recently it was shown that the popular dietary supplement chromium picolinate complex generates chromosome damage in hamster cells. In the United States the dietary guidelines for daily chromium uptake were lowered from 50-200 µg for an adult to 35 µg adult male and to 25 µg adult female.7 Isotopes Main article: Isotopes of chromium Naturally occurring chromium is composed of three stable isotopes; 52Cr, 53Cr, and 54Cr with 52Cr being the most abundant 83.789% natural abundance. Nineteen radioisotopes have been characterized with the most stable being 50Cr with a half-life of more than 1.8x1017 years, and 51Cr with a half-life of 27.7 days. All of the remaining radioactive isotopes have half-lives that are less than 24 hours and the majority of these have half-lives that are less than 1 minute. This element also has 2 meta states. 53Cr is the radiogenic decay product of 53Mn. Chromium isotopic contents are typically combined with manganese isotopic contents and have found application in isotope geology. Mn-Cr isotope ratios reinforce the evidence from 26Al and 107Pd for the early history of the solar system. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn-Cr isotope systematics must result from in-situ decay of 53Mn in differentiated planetary bodies. Hence 53Cr provides additional evidence for nucleosynthetic processes immediately before coalescence of the solar system. The isotopes of chromium range in atomic weight from 43 u 43Cr to 67 u 67Cr. The primary decay mode before the most abundant stable isotope, 52Cr, is electron capture and the primary mode after is beta decay. Precautions Chromium metal and chromiumIII compounds are not usually considered health hazards; chromium is an essential trace mineral.8 However, hexavalent chromium chromium VI compounds can be toxic if ingested or inhaled. The lethal dose of poisonous chromium VI compounds is about one half teaspoon of material. Most chromium VI compounds are irritating to eyes, skin and mucous membranes. Chronic exposure to chromium VI compounds can cause permanent eye injury, unless properly treated. ChromiumVI is an established human carcinogen. An investigation into hexavalent chromium release into drinking water formed the plot of the motion picture Erin Brockovich. World Health Organization recommended maximum allowable concentration in drinking water for chromium VI is 0.05 milligrams per liter. Hexavalent chromium is also one of the substances whose use is restricted by the European Restriction of Hazardous Substances Directive. In some parts of Russia, pentavalent chromium was reported as one of the factors of incidence of premature senility. 9 Chromium salts chromates are also the cause of allergic reactions in some people. Chromates are often used to manufacture, amongst other things, leather products, paints, cement, mortar and anti-corrosives. Contact with products containing chromates leads to allergic contact dermatitis and irritant dermatitis, resulting in ulceration of the skin, sometimes referred to as chrome ulcers. This condition is often found in workers that have been exposed to strong chromate solutions in electroplating, tanning and chrome-producing manufacturers. 10 As chromium compounds were used in dyes and paints and the tanning of leather, these compounds are often found in soil and groundwater at abandoned industrial sites, now needing environmental cleanup and remediation per the treatment of brownfield land. Primer paint containing hexavalent chromium is still widely used for aerospace and automobile refinishing applications. See also Chromium compounds Chromium minerals Chromium VI References Los Alamos National Laboratory - Chromium WebElements.com - Chromium ^ van der Krogt, Peter, Chromium, http://elements.vanderkrogt.net/elem/cr.html. Retrieved on 24 August 2008 ^ Cotterell, Maurice. 2004. The Terracotta Warriors: The Secret Codes of the Emperor's Army. Rochester: Bear and Company. ISBN 159143033X. Page 102. ^ Ignasi Puigdomenech, Hydra/Medusa Chemical Equilibrium Database and Plotting Software 2004 KTH Royal Institute of Technology, freely downloadable software at 1 ^ T. Nguyen, A. D. Sutton, M. Brynda, J. C. Fettinger, G. J. Long and P. P. Power 2005. Synthesis of a Stable Compound with Fivefold Bonding Between Two ChromiumI Centers. Science 310 5749: 844-847. doi:10.1126/science.1116789. PMID 16179432. ^ United States Patent 7271278 ^ ToxFAQs: Chromium. Agency for Toxic Substances Disease Registry, Centers for Disease Control and Prevention February 2001. Retrieved on 2007-10-02. ^ Vincent, J.B. 2007. Recent advances in the nutritional biochemistry of trivalent chromium. Proceedings of the Nutrition Society 63 01: 41-47. doi:10.1079/PNS2003315. ^ Chromium. Wellness Letter. ^ Chromium Toxicity on the Corrosion Doctors Web site maintained by Canadian Physical Chemist, Pierre R. Roberge, PhD, P.Eng. ^ Chrome Contact Allergy. DermNet NZ. External links Wikimedia Commons has media related to: Chromium Look up chromium in Wiktionary, the free dictionary. IARC Monograph Chromium and Chromium compounds International Chromium Development Association It's Elemental - The Element Chromium National Pollutant Inventory - Chromium III compounds fact sheet The Merck Manual - Mineral Deficiency and Toxicity National Institute for Occupational Safety and Health - Chromium Page v d e Periodic table H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo Alkali metals Alkaline earth metals Lanthanoids Actinoids Transition metals Other metals Metalloids Other nonmetals Halogens Noble gases Retrieved from http://en..org/wiki/Chromium Categories: Chemical elements | Transition metals | Chromium | Dietary minerals | Occupational safety and health Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages Afrikaans العربية Asturianu AzÉ™rbaycan বাংলা БеларуÑ?каÑ? Bosanski БългарÑ?ки Català Česky Corsu Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara Ù?ارسی Français Furlan Gaelg Galego í•œêµì–´ Õ€Õ¡ÕµÕ¥Ö€Õ¥Õ¶ हिनà¥?दी Hrvatski Ido Bahasa Indonesia Ã?slenska Italiano עברית ಕನà³?ನಡ Kiswahili Kreyòl ayisyen Kurdî / كوردی Latina LatvieÅ¡u Lëtzebuergesch Lietuvių Lojban Magyar МакедонÑ?ки മലയാളം MÄ?ori Bahasa Melayu NÄ?huatl Nederlands 日本語 ‪Norsk bokmÃ¥l‬ ‪Norsk nynorsk‬ Occitan O'zbek ਪੰਜਾਬੀ Plattdüütsch Polski Português Română Runa Simi РуÑ?Ñ?кий Shqip Sicilianu Simple English SlovenÄ?ina SlovenÅ¡Ä?ina СрпÑ?ки / Srpski Srpskohrvatski / СрпÑ?кохрватÑ?ки Seeltersk Suomi Svenska தமிழà¯? ไทย Tiếng Việt Türkçe УкраїнÑ?ька ä¸æ–‡ This page was last modified on 29 August 2008, at 12:06
39 Reasons to Drink Acai Juice Every Day
What is MonaVie - Watch the 8-minute video
Discovering MonaVie Video
The Power of You Video
Effects of MonaVie Active on Antioxidant Capacity in Humans
Log into your Wholesale MonaVie Account
So many of us do not eat a balanced diet, get enough sleep, have too much stress, or are impacted with toxins and pollutants. Drinking 2 ounces of MonaVie twice a day will help your body detoxify as well as build your immune system. Its the smartest thing you can do for yourself, so start today. Buying MonaVie through our company guarantees you support 7 days a week and, if you would like to share MonaVie with your family and friends we will guide you from start to finish.
1. Click on Enroll Now (30 - 55% off retail price)
2. Pay $39 for your Wholesale ID number.
3. NO minimum order required.
4. MonaVie is delivered to your door in 3 to 5 days.