Some properties of the rare-earth elements (values recommended by Ames Laboratory) part I
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▪ TableSome properties of the rare-earth elements (values recommended by Ames Laboratory) part Iscandium yttrium lanthanum ceriumatomic number 21 39 57 58atomic weight 44.956 88.905 138.91 140.12colour of element silvery silvery silvery silverymelting point (°C)1 1,541 1,522 9.21 799boiling point (°C)2 2,831 3,338 3,457 3,426density at 25 °C (grams per cubic centimetre) 2.9890 4.4689 6.1453 6.672conduction electrons in metal 3 3 3 3(3.1)valence in aqueous solution 3 3 3 3,4colour in aqueous solution colourless colourless colourless colourlesscolour of oxide white white white off-white (dicerium trioxide); cream (cerium dioxide)heat of fusion (kilocalories per gram atom) 3,369 2,732 1,482 1,238heat of vaporization2 (kilocalories per gram atom) 89.9 101.3 103.1 101.1electrical resistivity at 25 °C [ohm-centimetres(10−6)] 52 59 61–80 70–80Nèel point (°K) none none none 12.5Curie point (°K) none none none —compressibility at 25 °C [square centimetres per kilogram (10−6)] 2.26 2.68 4.04 4.10crystal structure3 hcp hcp d-hcp fccradius, metallic (angstroms) 1.640 1.801 1.879 1.820radius, ionic (angstroms) 0.732(+3) 0.893(+3) 1.061(+3) 1.034(+4, 0.92)praseodymium neodymium promethium samariumatomic number 59 60 61 62atomic weight 140.907 144.24 (145)4 150.35colour of element silvery silvery silvery silverymelting point (°C)1 931 1,021 1,168 1,077boiling point (°C)2 3,512 3,068 2,700 1,791density at 25 °C(grams per cubic centimetre) 6.773 7.007 — 7.520conduction electrons in metal 3 3 3 3valence in aqueous solution 3 3 3 3,2colour in aqueous solution green rose colourless yellowcolour of oxide black (hexapraseodymium undecaoxide); green (dipraseodymium trioxide) blue creamheat of fusion(kilocalories per gram atom) 1,652 1,705 — 2,061heat of vaporization2(kilocalories per gram atom) 85.3 78.5 — 49.2electrical resistivity at 25 °C [ohm-centimetres(10−6)] 68 65 — 91Nèel point (°K) — 20 — 15Curie point (°K) — — — —compressibility at 25 °C[square centimetres per kilogram (10−6)] 3.21 3.00 (2.8) 3.34crystal structure3 d-hcp hcp/bcc — rhombradius, metallic (angstroms) 1.828 1.821 — 1.804radius, ionic (angstroms) 1.013(+4, 0.90) 0.995(+3) 0.979(+3) 0.964(+2, 1.11)1Corrected for new temperature scale.2R. Hullgren, R. Orr, and K. Kelley.3hcp = hexagonal close-packed; fcc = face-centred cubic; rhomb = rhombohedral; bcc = body-centred cubic.4Radioactive isotope separated from fission residues.See as table:
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Universalium. 2010.
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rare-earth element — /rair errth /, Chem. any of a group of closely related metallic elements, comprising the lanthanides, scandium, and yttrium, that are chemically similar by virtue of having the same number of valence electrons. Also called rare earth metal. [1955 … Universalium
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