Stability ruler

We may generalize the results and conclusions of the stability ruler by noting that alkali metal and alkaline earth metal ions, lanthanides, and AP+ prefer oxygen donors transition metal ions, oxygen and nitrogen donors and the heavy metal ions, nitrogen and sulfur donors. For amplification of this topic, (see Hard Soft Acids and Bases). 

Hydroxo complex formation follows the same stability order as other ligands with the strongest binding at the right of the stability ruler in Table 3, where the hydroxide ion appears as the first entry. The stability ruler in Table 3 shows that both Zn + and Pb + exhibit a relatively strong tendency to form hydroxo complexes and precipitates. 

Cril R. Bruce Martin, "A Stability Ruler for Metal Ion Complexes," ]. Chem. Educ, Vol. 64,1987, 402. 

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