Why is Sodium Chloride White?
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Sodium chloride is colorless because the electrons are tightly bond tho the sodium cation and the chloride anion. Visible light has not enough energy to excite the electrons to higher energy levels. So there's no absorption or emission of visible light of a certain wavelength and therefore no color.
I wouldn't say that the majority of salts is colorless, since the more complex the composition of a salt is the more likely it is not colorless.
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Author by
Andi Gu
Updated on January 16, 2020Comments
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Andi Gu almost 4 years
Why is solid sodium chloride white - and for that matter, why are the majority of salts white in solid form?
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Mithoron almost 7 yearsPossible duplicate of Why is snow white?
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Mithoron almost 7 years
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MaxW almost 7 yearsI'll point out that in mineralogy a streak test (geology.com/minerals/streak-test.shtml) is used to help identify the mineral. The gist is that the color of the fine particles created by rubbing the mineral across a plate of alumina is observed. For any mineral of light color the streak will probably be white or whitish, but for very dark colored minerals a very different color can often be observed.
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Jan almost 7 yearsPossible duplicate of why are simple organic molecules usually white?
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orthocresol almost 7 yearsConsidering that sodium chloride is neither snow nor a simple organic molecule, I'm not sure how much of a duplicate this is. The argument has already been had in the comments on the latter question.
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porphyrin almost 7 yearsLarge perfect NaCl crystals are clear and colourless. When they are smashed about as in table salt they become fractured and surfaces scratched. Light is refracted through and reflected in all directions from the surface of the crystals. They now appear white due to this scattering provided the light source is 'white '. The reflections and scattering are caused by the difference in refractive index of the crystal and air. Put the crystals into an index matching liquid and they will appear transparent again. (There is a $1/\lambda^4$ dependence on scattering which can be seen in deep snow).
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Karl almost 7 years"Majority" is perhaps the wrong word, but practically all oxides, (pseudo-)halides, sulfates, nitrates etc. of main group metals are white, plus great many more. The big exception are compounds containing late transition metals, being often coloured.