Lanthanide thermodynamic properties

Schumm, R.H. Wagmann, D.D. Bailey, S. Evans, W.H. Parker, V.B. "Selected Values of Chemical Thermodynamic Properties" -Table for Lanthanide Elements", NBS-Technical Note 270-7, U.S. Govt. Printing Office, 1973. 

The ionic radii of the commonest oxidation states are presented in Table 2. There is evidence of an actinide contraction of ionic radii as the 5/ orbitals are filled and this echoes the well established lanthanide contraction of ionic radii as the 4/orbitals are filled. Actinides and lanthanides in the same oxidation state have similar ionic radii and these similarities in radii are obviously paralleled by similarities in chemical behaviour in those cases where the ionic radius is relevant, such as the thermodynamic properties observed for halide hydrolysis. 

This work was undertaken as a part of a study of divalent lanthanide halides in an effort to obtain more accurate thermal data on EuC12 and to determine if the close similarity of the high-temperature thermodynamic properties of divalent europium and alkaline earth compounds emphasized earlier (13-16) could be extended. 

These high temperature processes can be modelled adequately by equilibrium thermodynamics. For such calculations reliable thermodynamic data are a priority. Although numerous studies of the thermodynamic properties of the lanthanide trihalides have been published in the past, the available information is still not complete. But because the properties change regularly within the lanthanide series, estimates can help to obtain the data that are lacking. 

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