Manganese, 25 Manganese Pronunciation /ˈ m æ ŋ ɡ ə n iː z (MANG -gə-neez Appearance silvery metallic Standard atomic weight A r, std (Mn) 7001549380430000000♠ 54.938043 (2)[ 1] Manganese in theperiodic cairt Atomic nummer (Z ) 25 Group group 7 Period period 4 Block d-block Element category Transeetion metal Electron confeeguration [Ar ] 3d5 4s2 Electrons per shell 2, 8, 13, 2 Pheesical properties Phase at STP solit Meltin pynt 1519 K (1246 °C, 2275 °F) Bylin pynt 2334 K (2061 °C, 3742 °F) Density (near r.t.) 7.21 g/cm3 when liquid (at m.p.) 5.95 g/cm3 Heat o fusion 12.91 kJ/mol Heat o vapourisation 221 kJ/mol Molar heat capacity 26.32 J/(mol·K) Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1228 1347 1493 1691 1955 2333
Atomic properties Oxidation states −3, −2, −1, 0, +1,+2 +4 +7 amphoteric oxide) Electronegativity Pauling scale: 1.55 Ionisation energies Atomic radius empirical: 127 pm Covalent radius 139±5 (low spin), 161±8 (high spin) pm Colour lines in a spectral range Spectral lines o manganeseIther properties Naitural occurrence primordial Creestal structur body-centred cubic (bcc) Speed o soond thin rod 5150 m/s (at 20 °C) Thermal expansion 21.7 µm/(m·K) (at 25 °C) Thermal conductivity 7.81 W/(m·K) Electrical resistivity 1.44 µ Ω·m (at 20 °C) Magnetic orderin paramagnetic Young's modulus 198 GPa Bulk modulus 120 GPa Mohs haurdness 6.0 Brinell haurdness 196 MPa CAS Nummer 7439-96-5 History Diskivery Torbern Olof Bergman (1770) First isolation Johann Gottlieb Gahn (1774) Mainisotopes o manganese | references
Manganese is achemical element , designated bi the seembolMn . It haes theatomic nummer 25. It is foond as afree element in naitur (eften in combination wiiron ), an in monymeenerals . Manganese is a metal wi important industrial metalalloy uises, parteecularly instainless steels .
Historically, manganese is named forpyrolusite an ither black meenerals frae the region oMagnesia in Greece, that an aw gae its name taemagnesium an theairn uremagnetite . Bi the mid-18th century,Swadish- German chemist Carl Wilhelm Scheele haed uised pyrolusite tae producechlorine . Scheele an ithers war awaur that pyrolusite (nou kent tae bemanganese dioxide ) conteened a new element, but thay war unable tae isolate it.Johan Gottlieb Gahn wis the first tae isolate an impure saumple o manganese metal in 1774, that he did bireducin the dioxide wicaurbon .
Manganese phosphating is uised for roust an corrosion prevention onsteel . Ionised manganese is uised industrially aspigments o various colours, that depend on the oxidation state o the ions. Thepermanganates oalkali analkaline yird metals are pouerfu oxidisers. Manganese dioxide is uised as thecathode (electron acceptor) material inzinc-carbon analkaline batteries .
In biology, manganese(II) ions function ascofactors for a muckle variety oenzymes wi mony functions.[ 2] superoxide free radicals in organisms that maun deal wi elementaloxygen . Manganese an aw functions in the oxygen-evolvin complex o photosyntheticplants . While the element is a required trace meeneral for aw kent leevin organisms, it an aw acts as aneurotoxin in muckler amoonts. Espeicially throu inhalation, it can causemanganism , a condeetion in mammals leadin tae neurological damage that is whiles irreversible.
