Lithium anomalous” properties

Lithium has some chemical behavior that resembles the chemistry of Mg. Anomalous properties of Li result mainly from the small size of the atom and the ion the polarization power of Li+ is the greatest of all the alkali metal ions and leads to a singularly great tendency toward solvation and covalent bond formation. There is also evidence to suggest that lithium bonds comparable with hydrogen bonds exist in, e.g., H—F---Li—F and (LiF),.1... 

The small size of lithium frequently confers special properties on its compounds and for this reason the element is sometimes termed anomalous . For example, it is miscible with Na only above 380° and is immiscible with molten K, Rb and Cs, whereas all other pairs of alkali metals are miscible with each other in all proportions. (The ternary alloy containing 12% Na, 47% K and 41% Cs has the lowest known mp, —78°C, of any metallic system.) Li shows many similarities to Mg. This so-called diagonal relationship stems from the similarity in ionic size of the two elements / (Li ) 76pm, / (Mg ) 72pm, compared with / (Na ) 102pm. Thus, as first noted by Arfvedson in establishing lithium as a new element, LiOH and LiiCOs are much less soluble than the corresponding... 

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