Squeezing All Elements in the Periodic Table: Electron Configuration and Electronegativity of the Atoms under Compression

Abstract

We present a quantum mechanical model capable of describing isotropic compression of single atoms in a non-reactive neon-like environment. Studies of 93 atoms predict drastic changes to ground-state electronic configurations and electronegativity in the pressure range of 0–300 GPa. This extension of atomic reference data assists in the working of chemical intuition at extreme pressure and can act as a guide to both experiments and computational efforts. For example, we can speculate on the existence of pressure-induced polarity (red-ox) inversions in various alloys. Our study confirms that the filling of energy levels in compressed atoms more closely follows the hydrogenic aufbau principle, where the ordering is determined by the principal quantum number. In contrast, the Madelung energy ordering rule is not predictive for atoms under compression. Magnetism may increase or decrease with pressure, depending on which atom is considered. However, Hund’s rule is never violated for single atoms in the considered pressure range. Important (and understandable) electron shifts, s→p, s→d, s→f, and d→f are essential chemical and physical consequences of compression. Among the specific intriguing changes predicted are an increase in the range between the most and least electronegative elements with compression; a rearrangement of electronegativities of the alkali metals with pressure, with Na becoming the most electropositive s1 element (while Li becomes a p group element and K and heavier become transition metals); phase transitions in Ca, Sr, and Ba correlating well with s→d transitions; spin-reduction in all d-block atoms for which the valence d-shell occupation is d n (4 ≤ n ≤ 8); d→f transitions in Ce, Dy, and Cm causing Ce to become the most electropositive element of the f-block; f→d transitions in Ho, Dy, and Tb and a s→f transition in Pu. At high pressure Sc and Ti become the most electropositive elements, while Ne, He, and F remain the most electronegative ones.

Does Pressure Break Mirror‐Image Symmetry? A Perspective and New Insights

“…[27] Moreover, a theoretical survey of pressure effects for 93 elements of the periodic table indicates changes in ground-state electronic configurations and electronegativities in the range of 0-300 GPa. [28] Such pressure-induced structural changes have also been assessed in inherently chiral substances such as proteinogenic amino acids. [29][30][31] On increasing pressures, a varied polymorphism can be detected, some structures exhibiting large differential volumes and/or undergoing symmetry variations in the unit cell.…”

Physical origin of chemical periodicities in the system of elements

“…Indeed, the columns of the first Periodic Tables were labeled by "g-valent" by Meyer [20], and by the respective "EH g " and "E 2 O g " formulas of elements E in group g by Mendeleev [17][18][19] and some of his coevals. The common valence numbers of the elements are fundamental for standard chemistry in our human world (also including a part of geo-and cosmo-chemistry in our largescale surrounding), while the difference of core and valence shells fades away under very high pressure such as in the inner of the planets [67][68][69][70].…”

“…21 and 22). They indicate that the basic chemical rules may change quite a bit with the variation of the environmental conditions [67][68][69][70]. One must be careful when comparing elemental properties such as valence number or effective atomic radius with those under non-ambient conditions.…”

Quantum Chemical Modeling of Pressure‐Induced Spin Crossover in Octahedral Metal‐Ligand Complexes

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Spin state switching on external stimuli is a phenomenon with wide applicability, ranging from molecular electronics to gas activation in nanoporous frameworks. [6] In a metal-organic framework (MOF) with exposed Fe(II) sites, a distinct step as a function of atmospheric pressure has been observed in the adsorption isotherm of carbon monoxide, for which a cooperative spin-transition mechanism involving interacting iron centers in the MOF on introduction of the strong-field ligand carbon monoxide has been proposed. For spin crossover in first-row transition metals coordinated by hydrogen, nitrogen, and carbon monoxide, we find the pressure required for spin transition to be a function of the ligand position in the spectrochemical sequence.

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