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sarah12345
Hi i am a little stuck an how to work out the colour of a transition element from its absorbtion spectrum. ive got a past paper question and the main absorbance is just below 500nm where do i go from there?

thanks alot


The visible spectrum is from roughly 400-750nm with the blue end being at the lower end of this range.
As your compound absorbs below 500nm, ie the blue end of the spectrum, it will appear red/orange as these are the colours that are not absorbed.
Just remove the colours that are absorbed and make a guess at a colour from what is left! (in the end they should accept a range of colours in the markscheme).
there is a table of complementary colours.
check out this link
http://www.glenbrook.k12.il.us/gbssci/phys/class/light/u12l2d.html
AdditiveColorMixing.png

check this out. White light is made up of three colours. Absorb one and you are left with the mix of the other two.
eg: absorb red and you are left with the sum of the blue and the green = cyan

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