The coordination number of a complex refers to the number of ligands that are directly bonded to the central metal ion. In the case of UO2(NO3)3, the central metal ion is UO2, and it is coordinated to three NO3- ions. Each NO3- ion is bonded to the metal ion through one of its oxygen atoms, forming a bidentate chelating complex. Therefore, the coordination number of UO2(NO3)3 is 6.


The geometry of a complex is determined by the arrangement of its ligands around the central metal ion. In the case of UO2(NO3)3, the three NO3- ions are arranged around the UO2 ion in an octahedral geometry. The UO2 ion is located at the center of the octahedron, and the three NO3- ions occupy three of the six vertices of the octahedron. The bond angles between the UO2 ion and the NO3- ions are approximately 90 degrees, giving rise to a distorted octahedral geometry.


In summary, the coordination number of UO2(NO3)3 is 6, and its geometry is distorted octahedral, with the UO2 ion located at the center of the octahedron and the three NO3- ions occupying three of the six vertices of the octahedron.