| The actinides are characterized by a gradual filling of the 5 f-electron shell with the degree of localization increasing with the atomic number Z along the last series of the periodic table. The open shell of the 5f electrons determines the magnetic and solid-state properties of the actinide elements and their compounds and understanding the quantum mechanics of the 5f electrons with increasing prominence of relativistic effects is the defining issue in the physics and chemistry of the actinide elements. The 5f orbitals have properties intermediate between those of localized 4f and delocalized 3d orbitals and as such, the actinides constitute the "missing link" between the d transition elements and the lanthanides. Among the actinide elements, uranium is well known due its use as a nuclear reactor fuel and is the heaviest naturally occurring actinide element. It is located in the middle of the early part of the actinide series, with only three 5f electrons hybridizing with the 6d and 7s electrons and demonstrating itinerant behavior. (Abstract shortened by UMI.)... |
