Two well-known complex ions containing Ni are [Ni(H₂O)₆]²⁺, which is green, and [Ni(en)₃]²⁺, which is purple. Which one of these statements is true?

Question

Quizplus · Accepted Answer

The color of a complex ion is determined by the energy difference between the d orbitals in the metal atom, which is affected by the ligands surrounding the metal atom. The greater the splitting energy (Δ), the higher the frequency (and shorter wavelength) of light that is absorbed, leading to a complementary color in the visible spectrum. Since the purple complex absorbs higher frequency (and shorter wavelength) blue light, it must have a greater Δ than the green complex, which absorbs lower frequency (and longer wavelength) green light. Therefore, statement A is true. Statements B, C, D, and E are all false.

Two Well-Known Complex Ions Containing Ni Are [Ni(H2O)6]2+, Which Is

Two Well-Known Complex Ions Containing Ni Are [Ni(H₂O)₆]²⁺, Which Is