Chromium

Frae Wikipedia
Lowp tae: navigation, rake
Chromium,  24Cr
Chromium crystals and 1cm3 cube.jpg
General properties
Name, seembol chromium, Cr
Pronunciation /ˈkrmiəm/ KROH-mee-əm
Appearance sillery metallic
Chromium in the periodic cairt
Hydrogen (diatomic nonmetal)
Helium (noble gas)
Lithium (alkali metal)
Beryllium (alkaline yird metal)
Boron (metalloid)
Carbon (polyatomic nonmetal)
Nitrogen (diatomic nonmetal)
Oxygen (diatomic nonmetal)
Fluorine (diatomic nonmetal)
Neon (noble gas)
Sodium (alkali metal)
Magnesium (alkaline yird metal)
Aluminium (post-transeetion metal)
Silicon (metalloid)
Phosphorus (polyatomic nonmetal)
Sulfur (polyatomic nonmetal)
Chlorine (diatomic nonmetal)
Argon (noble gas)
Potassium (alkali metal)
Calcium (alkaline yird metal)
Scandium (transeetion metal)
Titanium (transeetion metal)
Vanadium (transeetion metal)
Chromium (transeetion metal)
Manganese (transeetion metal)
Iron (transeetion metal)
Cobalt (transeetion metal)
Nickel (transeetion metal)
Copper (transeetion metal)
Zinc (transeetion metal)
Gallium (post-transeetion metal)
Germanium (metalloid)
Arsenic (metalloid)
Selenium (polyatomic nonmetal)
Bromine (diatomic nonmetal)
Krypton (noble gas)
Rubidium (alkali metal)
Strontium (alkaline yird metal)
Yttrium (transeetion metal)
Zirconium (transeetion metal)
Niobium (transeetion metal)
Molybdenum (transeetion metal)
Technetium (transeetion metal)
Ruthenium (transeetion metal)
Rhodium (transeetion metal)
Palladium (transeetion metal)
Silver (transeetion metal)
Cadmium (transeetion metal)
Indium (post-transeetion metal)
Tin (post-transeetion metal)
Antimony (metalloid)
Tellurium (metalloid)
Iodine (diatomic nonmetal)
Xenon (noble gas)
Caesium (alkali metal)
Barium (alkaline yird metal)
Lanthanum (lanthanide)
Cerium (lanthanide)
Praseodymium (lanthanide)
Neodymium (lanthanide)
Promethium (lanthanide)
Samarium (lanthanide)
Europium (lanthanide)
Gadolinium (lanthanide)
Terbium (lanthanide)
Dysprosium (lanthanide)
Holmium (lanthanide)
Erbium (lanthanide)
Thulium (lanthanide)
Ytterbium (lanthanide)
Lutetium (lanthanide)
Hafnium (transeetion metal)
Tantalum (transeetion metal)
Tungsten (transeetion metal)
Rhenium (transeetion metal)
Osmium (transeetion metal)
Iridium (transeetion metal)
Platinum (transeetion metal)
Gold (transeetion metal)
Mercury (transeetion metal)
Thallium (post-transeetion metal)
Lead (post-transeetion metal)
Bismuth (post-transeetion metal)
Polonium (post-transeetion metal)
Astatine (metalloid)
Radon (noble gas)
Francium (alkali metal)
Radium (alkaline yird metal)
Actinium (actinide)
Thorium (actinide)
Protactinium (actinide)
Uranium (actinide)
Neptunium (actinide)
Plutonium (actinide)
Americium (actinide)
Curium (actinide)
Berkelium (actinide)
Californium (actinide)
Einsteinium (actinide)
Fermium (actinide)
Mendelevium (actinide)
Nobelium (actinide)
Lawrencium (actinide)
Rutherfordium (transeetion metal)
Dubnium (transeetion metal)
Seaborgium (transeetion metal)
Bohrium (transeetion metal)
Hassium (transeetion metal)
Meitnerium (unkent chemical properties)
Darmstadtium (unkent chemical properties)
Roentgenium (unkent chemical properties)
Copernicium (transeetion metal)
Ununtrium (unkent chemical properties)
Flerovium (post-transeetion metal)
Ununpentium (unkent chemical properties)
Livermorium (unkent chemical properties)
Ununseptium (unkent chemical properties)
Ununoctium (unkent chemical properties)
-

Cr

Mo
vanadiumchromiummanganese
Atomic nummer 24
Staundart atomic wicht (±) (Ar) 51.9961(6)
Element category   transeetion metal
Group, block group 6, d-block
Period period 4
Electron configuration [Ar] 3d5 4s1
per shell
2, 8, 13, 1
Pheesical properties
Phase solid
Meltin pynt 2180 K ​(1907 °C, ​3465 °F)
Boilin pynt 2944 K ​(2671 °C, ​4840 °F)
Density near r.t. 7.19 g/cm3
when liquid, at m.p. 6.3 g/cm3
Heat o fusion 21.0 kJ/mol
Heat o 339.5 kJ/mol
Molar heat capacity 23.35 J/(mol·K)
 pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1656 1807 1991 2223 2530 2942
Atomic properties
Oxidation states 6, 5, 4, 3, 2, 1, -1, -2 ​strongly acidic oxide
Electronegativity Pauling scale: 1.66
energies
(mair)
Atomic radius empirical: 128 pm
Covalent radius 139±5 pm
Miscellanea
Crystal structur body-centered cubic (bcc)
Body-centered cubic crystal structure for chromium
Speed o soond thin rod 5940 m/s (at 20 °C)
Thermal expansion 4.9 µm/(m·K) (at 25 °C)
Thermal conductivity 93.9 W/(m·K)
Electrical resistivity 125 n Ω·m (at 20 °C)
Magnetic orderin AFM (rather: SDW[1])
Young's modulus 279 GPa
Shear modulus 115 GPa
Bulk modulus 160 GPa
Poisson ratio 0.21
Mohs haurdness 8.5
Vickers haurdness 1060 MPa
Brinell haurdness 1120 MPa
CAS Registry Nummer 7440-47-3
History
Discovery Louis Nicolas Vauquelin (1797)
First isolation Louis Nicolas Vauquelin (1798)
Maist stable isotopes
Main article: Isotopes o chromium
iso NA hauf-life DM DE (MeV) DP
50Cr 4.345% >1.3×1018 y (β+β+) 1.167 50Ti
51Cr syn 27.7025 d ε - 51V
γ 0.320 -
52Cr 83.789% 52Cr is stable wi 28 neutrons
53Cr 9.501% 53Cr is stable wi 29 neutrons
54Cr 2.365% 54Cr is stable wi 30 neutrons
Decay modes in parentheses are predictit, but hae nae yet been observed
· references

Chromium is a chemical element which haes the seembol Cr an atomic nummer 24. It is the first element in Group 6. It is a steely-gray, lustrous, haird an brittle metal[2] which taks a heich polish, resists tarnishin, an haes a heich meltin pynt. The name o the element is derived frae the Greek wird χρῶμα, chrōma, meanin colour,[3] acause mony o its compoonds are intensely coloured.

References[eedit | eedit soorce]

  1. Fawcett, Eric (1988). "Spin-density-wave antiferromagnetism in chromium". Reviews of Modern Physics 60: 209. Bibcode:1988RvMP...60..209F. doi:10.1103/RevModPhys.60.209. 
  2. Brandes, E. A.; Greenaway, H. T.; Stone, H. E. N. (1956). "Ductility in Chromium". Nature 178 (587): 587. Bibcode:1956Natur.178..587B. doi:10.1038/178587a0. 
  3. χρῶμα, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus