Europium is a chemical element wi the seembol Eu an atomic nummer 63. It is named efter the continent Europe . It is a moderately haird, sillery metal whilk readily oxidizes in air an watter . Bein a teepical member o the lanthanide series, europium uisually assumes the oxidation state +3, but the oxidation state +2 is common an aa: aw europium compoonds wi oxidation state +2 are slichtly reducing . Europium haes na signeeficant biological role an is relatively non-toxic compared tae ither hivy metals . Maist applications o europium exploit the phosphorescence o europium compoonds.
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Europium, 63 Eu Europium Pronunciation (yoor-OH -pee-əm ) Appearance sillrry white, wi a pale yellsr tint;[1] but rarely seen without oxide discoloration Standard atomic weight A r, std (Eu)7002151964000000000♠ 151.964(1)[2] Europium in the periodic cairt
– ↑Eu ↓Am
samarium ← europium → gadolinium
Atomic nummer (Z ) 63 Group group n/a Period period 6 Block f-block Element category Lanthanide Electron confeeguration [ Xe ] 4f7 6s2 Electrons per shell 2, 8, 18, 25, 8, 2 Pheesical properties Phase at STP solid Meltin pynt 1099 K (826 °C, 1519 °F) Bylin pynt 1802 K (1529 °C, 2784 °F) Density (near r.t. ) 5.264 g/cm3 when liquid (at m.p. ) 5.13 g/cm3 Heat o fusion 9.21 kJ/mol Heat o vapourisation 176 kJ/mol Molar heat capacity 27.66 J/(mol·K) Vapour pressur
P (Pa)
1
10
100
1 k
10 k
100 k
at T (K)
863
957
1072
1234
1452
1796
Atomic properties Oxidation states +1, +2 , +3 (a mildly basic oxide) Electronegativity Pauling scale: 1.2 Ionisation energies 1st: 547.1 kJ/mol 2nd: 1085 kJ/mol 3rd: 2404 kJ/mol Atomic radius empirical: 180 pm Covalent radius 198±6 pm Colour lines in a spectral range Spectral lines o europiumIther properties Naitural occurrence primordial Creestal structur bouk-centred cubic[[File:bouk-centred cubic|frameless|alt=Bouk-centred cubic creestal structur for europium|upright=0.23|Bouk-centred cubic creestal structur for europium]]
Thermal expansion poly: 35.0 µm/(m·K) (at r.t. ) Thermal conductivity est. 13.9 W/(m·K) Electrical resistivity poly: 0.900 µΩ·m (at r.t. ) Magnetic orderin paramagnetic [3] Magnetic susceptibility +34,000.0·10−6 cm3 /mol[4] Young's modulus 18.2 GPa Shear modulus 7.9 GPa Bulk modulus 8.3 GPa Poisson ratio 0.152 Vickers haurdness 165–200 MPa CAS Nummer 7440-53-1 History Namin efter Europe Diskivery an first isolationEugène-Anatole Demarçay (1896, 1901)Main isotopes o europium
Iso tope
Abun dance
Hauf-life (t 1/2 )
Decay mode
Pro duct
150 Eu
syn
36.9 y
ε
150 Sm
151 Eu
47.8%
5×1018 y
α
147 Pm
152 Eu
syn
13.54 y
ε
152 Sm
β−
152 Gd
153 Eu
52.2%
stable
154 Eu
syn
8.59 y
β−
154 Gd
155 Eu
syn
4.76 y
β−
155 Gd
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Greenwood, Norman N. ; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth–Heinemann . p. 112. ISBN 0080379419 .Weast, Robert (1984). CRC, Handbook of Chemistry and Physics . Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4 .