Polyvalent s-block elements: A missing link challenges the periodic law of chemistry for the heavy elements.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37856546.
- Also identified by DOI 10.1073/pnas.2303989120 and PMC identifier 10614932.
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Abstract
The Periodic Law of Chemistry is one of the great discoveries in cultural history. Elements behaving chemically similar are empirically merged in groups <i>G</i> of a Periodic Table, each element with <i>G</i> valence electrons per neutral atom, and with upper limit <i>G</i> for the oxidation and valence numbers. Here, we report that among the usually mono- or di-valent s-block elements (<i>G</i> = 1 or 2), the heaviest members (<sub>87</sub>Fr, <sub>88</sub>Ra, <sub>119</sub>E, and <sub>120</sub>E) with atomic numbers Z = 87, 88, 119, 120 form unusual 5- or 6-valent compounds at ambient conditions. Together with well-reported basic changes of valence at the end of the 6d-series, in the whole 7p-series, and for 5g6f-elements, it indicates that at the bottom of common Periodic Tables, the classic Periodic Law is not as straightforward as commonly expected. Specifically, we predict the feasible experimental synthesis of polyvalent [RaL<sup>-</sup><sub><i>n</i></sub>] (<i>n</i> = 4, 6) compounds.