Why Gold has the colour it has??

Gold as everyone knows is a noble metal sought after by everyone. By being noble means it is resistant to chemical reactions like corrosion by air and water combination.

The answer tothe question why it has the colour it has lies in electronic configuration of gold atoms.  Its electronic configuration is [Xe] 4f14 5d10 6s1 where Xe stands for Xenon. The outermost orbitals are 5d and 6s.  There is one electron in the outermost shell. In the geometric structure, atoms are arranged in a particular config And the lone electrons present the 6s orbitals are diffused in the lattice which means that individual electron in a atom has lost the address of parent atom and now belong to the community of gold atoms.

How do the objects we see have different colours? Colours are hidden in white light emanating from the sun. The visible spectrum of light components is composite of 7 colours remembered using “VIBGYOR” where V is for violet and has the maximum energy in the visible spectrum and R is for red with lowest energy.

When it falls on an object, the object absorbs some fraction of the light and reflects the rest of it. Which color or colors wavelengths it will absorb depends upon the unique structure of the object molecules. We see the resultant of colours which are reflected.

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In case of gold, the energy difference between the 5d and 6s levels is 2.7 electron volts. The blue light has exactly this energy in its photon packets. So when light falls on it, it completely absorbs the blue fraction of the light. The remains reflected resultant light is exactly the colour which is that of gold.

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Author: Ranjit Singh

I am working as a scientist in the India's premium E&P oil company. Besides the commitment to my job, I read lot of literature especially good fiction, history and science. I belong to Chandigarh and did my Masters in Chemistry from Panjab University Chandigarh specializing in physical chemistry. I am fond of surfing the internet for good articles, social networking and giving vent to writing for which I have aptly chosen the blog in Wordpress. Thanks

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