Why D Block Elements Form Colored Compounds

The d block elements form colored compounds primarily due to the presence of unpaired d electrons. According to the NCERT syllabus, the color of these compounds is due to the electronic transitions that occur between different d orbitals. When light falls on these compounds, electrons in the lower energy d orbitals get excited to higher energy d orbitals. This process is known as a d-d transition. The specific wavelength of light absorbed during this transition determines the color of the compound. The remaining wavelengths of light are transmitted or reflected, which gives the compound its characteristic color.