Electrons and Quantum Mechanics - Oakland Schools

Disposal
Discussion
Solutions may be flushed down the drain with ample water.
In water solutions, transition metal ions are usually not found as single ions but
as complex ions in which the metal ion is bonded to 2, 4, or 6 water molecules
with coordinate covalent bonds. If the water solution is mixed with another
species which can donate electrons to the metal, a new complex ion with the
new species may be formed. The various species which can complex with metal
ions are referred to as ligands. Often the color of the new complex ion is
different from the original color of the metal ion in water.
The color of the complex arises from the crystal field splitting of the five
degenerate d orbitals into 2 energy levels by certain liqands.
The energy gap, labeled E, between the d orbitals is on the same order of
magnitude as the energy of a photon of visible light. The actual magnitude of E
for a given complex and therefore the color of the complex is determined by the
following: which ligand is used; which metal is used and the oxidation state of
the metal. Thus, the color of the complex ion can be used to determine the
wavelength of light absorbed by using the color rosette shown.
Source: Shakhashiri
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