What is the reason behind visual properties like color and transparency of different substances? I have always heard that the structure of the substance is responsible for these properties. I always imagined that the bond length between the atoms of the substance permits photons of only some certain wavelength. But, most bonds are in the order of $1.5\unicode{xC5} $, and by my "explanation", most materials should appear to be opaque (in the visible spectrum), but they don't. Why?

  • $\begingroup$ AvZ: have a look through the results you get if you search this site for transparent $\endgroup$ Commented Sep 23, 2014 at 15:55
  • $\begingroup$ I did exactly that before I submitted the question, It went to google search of the site which didn't return any similar questions... $\endgroup$
    – AvZ
    Commented Sep 23, 2014 at 15:56
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    $\begingroup$ Is the "color" portion of this question also a duplicate? $\endgroup$
    – BMS
    Commented Sep 23, 2014 at 16:47