Cerium

Cerium is a chemical element wi seembol Ce an atomic nummer 58. It is a saft, silvery, ductile metal which easily oxidizes in air. Cerium wis named efter the dwarf planet Ceres (itsel named for the Roman goddess o agricultur). Cerium is the maist abundant o the rare yird elements, makin up aboot 0.0046% o the Yird's crust bi wicht. It is foond in a feck o minerals, the maist important bein monazite an bastnasite. Thare a wheen o ommercial applications o cerium. Thay include catalysts, additives fur tae fuel tae reduce emissions an tae gless an enamels tae chynge thair colour. Cerium oxide is an important component o gless polishin pouders an phosphors uised in screens an fluorescent lamps. It is uised in the "flint" (actually ferrocerium) o lichters.

Cerium, ₅₈Ce

Cerium
Pronunciation	/ˈsɪəriəm/ ​(SEER-ee-əm)
Appearance	sillery white
Standard atomic weight Ar, std(Ce)	7002140116000000000♠140.116(1)[1]
Cerium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium - ↑ Ce ↓ Th lanthanum ← cerium → praseodymium
Atomic nummer (Z)	58
Group	group n/a
Period	period 6
Block	f-block
Element category	Lanthanide
Electron confeeguration	[Xe] 4f1 5d1 6s2[2]
Electrons per shell	2, 8, 18, 19, 9, 2
Pheesical properties
Phase at STP	solit
Meltin pynt	1068 K ​(795 °C, ​1463 °F)
Bylin pynt	3716 K ​(3443 °C, ​6229 °F)
Density (near r.t.)	6.770 g/cm3
when liquid (at m.p.)	6.55 g/cm3
Heat o fusion	5.46 kJ/mol
Heat o vapourisation	398 kJ/mol
Molar heat capacity	26.94 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1992 2194 2442 2754 3159 3705
Atomic properties
Oxidation states	+1, +2, +3, +4 (a mildly basic oxide)
Electronegativity	Pauling scale: 1.12
Atomic radius	empirical: 181.8 pm
Covalent radius	204±9 pm
Spectral lines o cerium
Ither properties
Naitural occurrence	primordial
Creestal structur	​face-centred cubic (fcc)
Speed o soond thin rod	2100 m/s (at 20 °C)
Thermal expansion	(r.t.) (γ, poly) 6.3 µm/(m·K)
Thermal conductivity	11.3 W/(m·K)
Electrical resistivity	(r.t.) (β, poly) 828 n Ω·m
Magnetic orderin	paramagnetic[3]
Young's modulus	(γ form) 33.6 GPa
Shear modulus	(γ form) 13.5 GPa
Bulk modulus	(γ form) 21.5 GPa
Poisson ratio	(γ form) 0.24
Mohs haurdness	2.5
Vickers haurdness	270 MPa
Brinell haurdness	412 MPa
CAS Nummer	7440-45-1
History
Namin	efter dwarf planet Ceres, itsel named efter Roman deity o agricultur Ceres
Diskivery	Martin Heinrich Klaproth, Jöns Jakob Berzelius, Wilhelm Hisinger (1803)
First isolation	Carl Gustaf Mosander (1839)
Main isotopes o cerium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 134Ce syn 3.16 d ε 134La 136Ce 0.185% >3.8×1016 y (β+β+) 136Ba 138Ce 0.251% >1.5×1014 y (β+β+) 138Ba 139Ce syn 137.640 d ε 139La 140Ce 88.450% - (SF) 141Ce syn 32.501 d β− 141Pr 142Ce 11.114% >5×1016 y (β−β−) 142Nd (α) 138Ba 144Ce syn 284.893 d β− 144Pr
Decay modes in parentheses is predict, but hisna yet been observed
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