Abstract:
Superheavy elements(SHEs), defined as elements with atomic numbers greater than 103, represent a frontier in nuclear and chemical sciences. These elements, which include rutherfordium(Rf) through oganesson(Og), are not exist in nature and currently can only be artificially synthesized using heavy-ion accelerators. The production of SHEs is characterized by extremely low yields, often resulting in only “one-atom-at-a-time” level, and all their isotopes have short half-lives, typically ranging from milliseconds to seconds. These characteristics preclude their detection through conventional chemical analysis techniques, resulting in limited understanding of their chemical properties and behavior. In addition, with the increasing atomic number, relativistic effects become increasingly pronounced, significantly impacting the physical and chemical properties of SHEs. Consequently, the chemical behavior of SHEs deviates markedly from periodicity-based predictions for their lighter homologs. To be precise, the position of a new element in the periodic table can only be definitively assigned after verifying its chemical property. Therefore, investigating the chemical properties of SHEs is a critical research issues in nuclear chemistry. In this case, gas phase chromatography technique was developed as a distinctive and effective method for examining the volatility, adsorption enthalpy, and other essential physicochemical parameters of short-lived SHEs. Through such approaches, researchers can infer the chemical behavior of single atoms of superheavy elements and compare them with predictions from relativistic quantum chemical calculations. This review systematically explores advancements in the gas-phase chemistry of SHEs, encompassing historical developments, experimental methodologies, recent discoveries, status and progress in China. Its objective is to clarify the impact of relativistic effects on their electron configurations and their precise positions within the periodic table. The article reviews the discovery process of SHEs, from the pioneering efforts in the late 20th century until more recent achievements in synthesizing of the heaviest element, and highlights significant technological advancements in their chemical research, including the developments of target preparation and gas chromatography technology. Moreover, the detailed insights into recent experimental methods and results concerning carbonyl complexes of seaborgium(Sg), bohrium(Bh), hassium(Hs), meitnerium(Mt) and their homologues, as well as the chemical properties of copernicium(Cn), nihonium(Nh), flerovium(Fl), and even moscovium(Mc) in their elemental states are presented. Recent studies confirm that, although the chemical properties of SHEs generally follows the periodic trends observed in their lighter homologs, they also exhibit deviations due to the strong relativistic effects on the electron configurations. From a future perspective, anticipated advancements in experimental techniques and theoretical models will further elucidate the underlying principles of the periodic table and enable the exploration of heavier elements.