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An essay on periodic tables

2019; International Union of Pure and Applied Chemistry; Volume: 91; Issue: 12 Linguagem: Inglês

10.1515/pac-2019-0801

1365-3075

Pekka Pyykkö,

Twentieth Century Scientific Developments

Abstract After a compact history of the PT, from Döbereiner’s triads to the theoretical predictions up to element 172, a number of particular issues is discussed: Why may Z = 172 be a limit for stable electron shells? What are the expected stability limits of the nuclear isotopes? When are formally empty atomic orbitals used in molecular electronic structures? What is ‘Secondary Periodicity’? When do the elements (Ir, Pt, Au), at the end of a bond, simulate (N, O, I), respectively? Some new suggestions for alternative PTs are commented upon. As a local connection, Johan Gadolin’s 1794 analysis of the Ytterby mineral is mentioned.