Does coal not sparkle because of its colour or because light does not refract / reflect from the cut facets? Thanks!
In: Physics
Maybe off-topic but here’s why diamonds are transparent:
A diamond consists of a 3 dimensional array of carbon atoms bound together. A chemical bond is just electrons moving around two atoms binding them together by electrostatic forces. Electrons can absorb light, which raises their energy level, and they loose the energy in form of heat for example. When a compound absorbs light (=the bond electrons absorb light), and that light has a wavelength within the visible spectrum, the compound has a color. When every visible wavelenth gets absorbed, the compound is black.
More tightly bound electrons need more energy (=smaller wavelength of light) to be excited to higher energy levels. Lets compare diamonds and graphite. The electrons in diamond are too tightly bound to the carbon atoms , they only absorb high energy UV light, which is invisible – so diamonds absorb no color, they are transparent. The carbon atoms in graphite are arranged in sheets, and these sheets are bound together by weaker bonds called pi-bonds. These pi-bond electrons absorb light at almost every wavelength in the visible spectrum – so graphite is black. These pi-bonds are also the reason why graphite conducts electricity and diamonds don’t.
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