Trivalent ions in aqueous solution

In summary, actinides in the oxidation stage M(III) form trivalent ions in aqueous solution with chemical properties similar to those of the trivalent tare earths, e.g., lanthanum. The M(IV) actinides form tetravalent ions with properties characteristic of Th. The M(V) actinides form MOj" ions, and the M(VI) form ions whose properties are characteristic of The... 

Before its discovery, nobelium was expected to be a trivalent ion in aqueous solution and to exhibit a chemical behavior similar to the elements preceding it in the actinide series. However, in 1949, Seaborg predicted that a relatively stable 2-t-state might exist for element 102 due to the special stability of the filled 5f electronic configuration [55], Twenty years later, this prediction was confirmed. 

Since Lr is a trivalent ion in aqueous solution, it should exhibit a chemical behavior similar to the other 3 -i- actinides and lanthanides, e.g. insoluble fluoride and hydroxide. One would expect Lr to have a slightly smaller ionic radius than Md and to elute before Md from a Dowex 50 cation-exchange resin column using a-hydroxyisobutyric add as eluant (see Fig. 13.1). David et al. have estimated an ionic radius of0.893 A for Lr and a metallic radius of 1.71 A for trivalent Lr [12]. Nugent has calculated values of — 2.0 V for E° (Lr - Lr) and -1-7.9 V for °(Lr " Lr " ) [68]. 

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