Some properties of the rare-earth elements (values recommended by Ames Laboratory) part I

Some properties of the rare-earth elements (values recommended by Ames Laboratory) part I

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Some properties of the rare-earth elements (values recommended by Ames Laboratory) part I
scandium yttrium lanthanum cerium
atomic number 21 39 57 58
atomic weight 44.956 88.905 138.91 140.12
colour of element silvery silvery silvery silvery
melting point (°C)1 1,541 1,522 9.21 799
boiling point (°C)2 2,831 3,338 3,457 3,426
density at 25 °C (grams per cubic centimetre) 2.9890 4.4689 6.1453 6.672
conduction electrons in metal 3 3 3 3(3.1)
valence in aqueous solution 3 3 3 3,4
colour in aqueous solution colourless colourless colourless colourless
colour 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 1,238
heat of vaporization2 (kilocalories per gram atom) 89.9 101.3 103.1 101.1
electrical resistivity at 25 °C [ohm-centimetres(10−6)] 52 59 61–80 70–80
Nèel point (°K) none none none 12.5
Curie point (°K) none none none —
compressibility at 25 °C [square centimetres per kilogram (10−6)] 2.26 2.68 4.04 4.10
crystal structure3 hcp hcp d-hcp fcc
radius, metallic (angstroms) 1.640 1.801 1.879 1.820
radius, ionic (angstroms) 0.732
(+3) 0.893
(+3) 1.061
(+3) 1.034
(+4, 0.92)
praseodymium neodymium promethium samarium
atomic number 59 60 61 62
atomic weight 140.907 144.24 (145)4 150.35
colour of element silvery silvery silvery silvery
melting point (°C)1 931 1,021 1,168 1,077
boiling point (°C)2 3,512 3,068 2,700 1,791
density at 25 °C
(grams per cubic centimetre) 6.773 7.007 — 7.520
conduction electrons in metal 3 3 3 3
valence in aqueous solution 3 3 3 3,2
colour in aqueous solution green rose colourless yellow
colour of oxide black (hexapraseodymium undecaoxide); green (dipraseodymium trioxide) blue cream
heat of fusion
(kilocalories per gram atom) 1,652 1,705 — 2,061
heat of vaporization2
(kilocalories per gram atom) 85.3 78.5 — 49.2
electrical resistivity at 25 °C [ohm-centimetres(10−6)] 68 65 — 91
Nèel point (°K) — 20 — 15
Curie point (°K) — — — —
compressibility at 25 °C
[square centimetres per kilogram (10−6)] 3.21 3.00 (2.8) 3.34
crystal structure3 d-hcp hcp/bcc — rhomb
radius, metallic (angstroms) 1.828 1.821 — 1.804
radius, 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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