Final answer:
Crystal Field Theory (CFT), developed in the 1920s, is a bonding model that addresses the properties of transition metal complexes, explaining their colors, magnetism, and structures through electrostatic interactions between metal ions and ligands.
Step-by-step explanation:
The theories developed in the 1920s to predict molecular/mineral structures for ionically bonded atoms are Pauling's rules. However, the principle that was developed to specifically address the behavior of transition metal complexes, including their color, magnetic behavior, and structures, is known as Crystal Field Theory (CFT). Crystal Field Theory postulates that the interactions between a central metal ion and surrounding ligands are electrostatic and that these interactions result in a split of the metal atom's d orbitals into different energy levels, giving rise to various observable properties. CFT is key in understanding why transition-metal complexes exhibit the wide array of colors and magnetic properties that they do. While CFT assumes metal-ligand interactions to be purely electrostatic, this simplification enables chemists to accurately predict many characteristics of coordination compounds.