Lanthanide electron affinity

The Ea for the d block elements can be supported by theoretical estimates. However, the experience with lanthanides suggests that calculations presently give lower limits to the actual values because of the difficulties of relativity and electron correlation effects. The determination of more precise and accurate experimental values should improve these calculations. For the present the only conclusion that can be reached for the transition elements is that lower limits to the adiabatic electron affinity have been measured and that some of them are equal to the adiabatic electron affinities based on periodic trends. 

I.r. spectra of some lanthanide disulphides have been measured and the presence of —S—S groups has been demonstrated. Values for the electron affinities of Se , and Te have been calculated as part of a study of the properties of alkaline-earth sulphides, selenides, and tellurides. Thermodynamic data for the sulphides of Fe, Co, and Ni have been related to the pH of their precipitation. The standard enthalpy of formation for the non-stoicheiometric sulphide Fe,, S has been deduced. Thermodynamic data for some lead chal-cogenides have been determined. ... 

Periodic Table of Electron Affinities (kJ/mol) The values listed in parentheses in this periodic table of electron affinities are approximate. Electron affinity is estimated to be —50 kJ/mol for each of the lanthanides and 0 kJ/mol for each of the actinides. 

Here, W is the lattice energy, which is actually the enthalpy of formation of the crystal lattice from ions in the gaseous state lEi and IE2 are the first and second lEs of the lanthanide AatH°(Cl2, 0) is the atomization energy of CI2 and EA(Cl) is the electron affinity of chlorine at T = 0. 

Indeed, if we use refined values of the first and second lEs of lanthanide atoms from the NIST website or from the CRC Handbook (2000-2001) (cf. Table 53) in calculating the lattice energies and if we take the enthalpies of formation listed in Table 52, the enthalpy of atomization of molecular chlorine (AatH (Cl2, 0) = 239.240 kj/mol) and the electron affinity of atomic chlorine EA(Cl) = 348.700 kJ/mol from... 

In 1994, we began our first calculations on the electron affinities of the rare earths [8], These are the most difficult atoms to treat, due to the open /-subshells, followed by the transition metal atoms with their open ri-subshells. At that time, some accelerator mass spectrometry (AMS) measurements of the lanthanides existed [9,10] which were rough. Larger values might be due to multiple bound states, states were uncharacterized as to dominant configuration, etc. 

Explain the important distinctions between each pair of terms (a) actinide and lanthanide element (b) covalent and metallic radius (c) atomic number and effective nuclear charge (d) ionization energy and electron affinity (e) paramagnetic and diamagnetic. 

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