The stability of metal complexes is affected by various ligand and metal factors. Ligand factors that increase stability include small size, high charge, chelation which forms multiple bonds to the metal, and high basicity. Steric effects from bulky ligands decrease stability. For the metal, higher charge and smaller size increase stability, as do behaviors defined by the Ahrland-Chatt classification like class A metals forming more stable complexes with lighter donor atoms. The Irving-Williams series and crystal field theory show transition metal complex stability follows trends based on ionic radius, crystal field splitting, and effects like Jahn-Teller distortion.