Members of this group tend to lose three electrons, usually 5-d-1 and the 6-s-2, to obtain their most stable configuration.  
The Sparkle Model is a computational modeler that predicts the geometries of the constituents of this chemical group.  Its members obey the Oddo-Harkins rule, which states that odd-numbered members are less abundant than even-numbered ones.  Members of this group tend to lose three electrons, usually 5-d-1 and the 6-s-2, to obtain their most stable configuration.  The decrease in ionic radius across the series is known as its namesake contraction.  Comprising the 4f electron shell elements, FTP, identify this series of the Periodic Table named after its first member, element number 57.
The Sparkle Model is a computational modeler that predicts the geometries of the constituents of this chemical group.  
lanthanide series or lanthanoid series