Question

This is for my Beer's Law Lab (Pre-Lab Questions)

Explain why a compound like iron (II) chloride is yellow and a compound of copper (II) is teal but the compounds sodium chloride and magnesium chloride are white.

Answer 1

Copper and Iron are transition metal atoms, which means they have d-orbitals present which allow for the electronic transitions whose wavelength falls in the visible light range.

Sodium and Magnesium are not transition metal atoms and they do not absorb light in the visible spectrum.

Copper and Iron absorb wavelengths in this range, and they appear to be of a color complementary to the color absorbed. Na and Mg don't absorb in the visible range.

Hope this helps !