The complex ions of Zn2+ are colorless. Why?

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Think unpaired vs paired electrons?

Since Zn2+ is a d10 ion, it does not absorb visible light even though the “d orbital” splittings are correct for absorbing visible wavelengths. Meaning that all d orbitals are full therefore there is no space for the electrons to move resulting in a colorless compound

To understand why complex ions of Zn2+ are colorless, we need to consider the electron configuration of the zinc ion.

Zinc (Zn) is a transition metal located in Group 12 of the periodic table. The electron configuration of neutral zinc is [Ar] 3d10 4s2. When zinc loses two electrons to form the Zn2+ ion, its electron configuration becomes [Ar] 3d10.

In transition metal compounds, the color is often due to the presence of unpaired electrons in partially filled d orbitals. These unpaired electrons can absorb certain wavelengths of light, resulting in the observed color.

However, in the case of Zn2+ ions, there are no unpaired electrons present in the d orbitals. The 3d orbitals are completely filled with 10 electrons, rendering them paired. As a result, Zn2+ ions do not absorb visible light in the range of wavelengths that contribute to color perception. Therefore, complex ions of Zn2+ are colorless.

In summary, the lack of unpaired electrons in the d orbitals of Zn2+ ions is the reason for their colorlessness.

The complex ions of Zn2+ are colorless because the electronic configuration of the Zn2+ ion does not have any unpaired electrons in its d-orbitals. The color of transition metal complexes is attributed to the presence of unpaired electrons in the d-orbitals, which can absorb certain wavelengths of light and appear colored. Since Zn2+ does not have any unpaired electrons, it does not absorb visible light and therefore appears colorless.