Abstract

Mendeleev in his first publication ordered the chemical elements following an apparent periodicity of properties such as atomic volume and valence. The reactivity of the elements was only studied systematically many years later. To illustrate the systematic variation of kinetics across the periodic table we compare water residence times for monoatomic ions in aqueous solution. A tremendous variation of tau(H2O) by over 20 orders of magnitude is found, ranging from similar to 10 ps to about 200 years. Apart from some small +2 and +3 cations, all main group elements have very short residence times <10 ns. Transition metal cations of the d-block have water residence times that depend on the electronic configuration. tau(H2O )of lanthanide ions are surprisingly short with values of 10 ns and shorter. This is due to an equilibrium between 8 and 9 coordinated ions leading to a low energy of the transition state for the water exchange reaction.

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