Chemical Studies of Rutherfordium (Rf) and Nobelium (No) on an Atom-at-a-time Scale

Abstract

Chemistry of the transactinide elements with atomic numbers (Z) ≥ 104 is one of the most fascinating and challenging subjects in the research field of nuclear and radiochemistry. At present, the elements up to element 118 are reported to be produced in heavy-ion-induced nuclear reactions. 2 The position of these elements at the Periodic Table is of fundamental importance. Pioneering chemical works performed with a few of atoms have thus far experimentally verified to place the transactinide elements on respective positions at the Periodic Table (see Figure 1). Rutherfordium (Rf) through hassium (Hs) 3, 4 and copernicium (Cn) are arranged on the groups 4 to 8 and 12 in the newly appearing 6d transition series, respectively. Very recently, chemical behavior of element 114 was reported to deviate from the systematic trend in that of lighter group-14 elements although further confirmation is necessary. It is of special interest to study chemical properties of the transactinide elements in detail to elucidate the influence of increasingly strong relativistic effects. Relativistic mass increase of electrons due to its velocity approaching to the speed of light enforces the contraction and stabilization of s and p1/2 orbitals. The increased screening by these contracted orbitals for a positive nuclear charge makes outer p3/2, d, and f orbitals expanded and destabilized. Relativistic contribution also comes from the spin-orbit splitting of electron orbitals Chemical Studies of Rutherfordium (Rf) and Nobelium (No) on an Atom-at-a-time Scale