If any element their last orbit is incomplete than they make coloured Salt. last orbit is complete than make colourless salts. cu forms coloured Salt .Zn forms colourless salts

Formation of Colored Salts by Cu

Copper (Cu) is a transition metal that forms colored salts due to the presence of partially filled d orbitals in its valence shell. This phenomenon occurs because of the absorption and reflection of specific wavelengths of light by the metal ions in the salt.

Electronic Configuration of Copper

Cu has an atomic number of 29, and its electronic configuration is [Ar] 3d^10 4s^1. The partially filled d orbitals (3d^10) in the valence shell of Cu allow it to exhibit unique properties, including the ability to form colored salts.

Absorption and Reflection of Light

When light interacts with a substance, it can be absorbed, transmitted, or reflected. The color of a substance is determined by the wavelengths of light that are absorbed and reflected by its molecules or ions. In the case of copper salts, the partially filled d orbitals can absorb specific wavelengths of light in the visible spectrum, resulting in the perception of color.

Formation of Colored Copper Salts

When copper reacts with other elements or compounds, it can form various salts. The characteristic colors of these salts are due to the absorption and reflection of specific wavelengths of light by the copper ions present in the salt.

For example, copper sulfate (CuSO4) is a blue-colored salt. The blue color arises from the absorption of light in the red and yellow regions of the visible spectrum, while the blue wavelengths are reflected and transmitted. This selective absorption of light by the copper ions in the salt gives it its distinct color.

Formation of Colorless Salts by Zn

Unlike copper, zinc (Zn) is not a transition metal and does not have any partially filled d orbitals in its valence shell. As a result, zinc salts do not exhibit any characteristic color and appear colorless.

Electronic Configuration of Zinc

Zinc has an atomic number of 30, and its electronic configuration is [Ar] 3d^10 4s^2. The completely filled d orbitals in the valence shell of zinc do not allow for the absorption and reflection of specific wavelengths of light, leading to the absence of color in its salts.

Conclusion

In summary, the formation of colored salts by copper and colorless salts by zinc can be attributed to the electronic configurations of these elements. The presence of partially filled d orbitals in copper allows it to absorb and reflect specific wavelengths of light, resulting in the perception of color in its salts. On the other hand, the absence of partially filled d orbitals in zinc prevents it from exhibiting any characteristic color in its salts.