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    Hi guys,

    I ve mashallah complete hands on for phase, pH and mass spectrometry. if anyone would like to ask an the above topics they are welcome. I'll try to solve ur questions and help the ones who seek.

    I would like u to help in how the colours of tranistion metals are formed. ( I studied from various books but I am not clear-confusion lingers in my head)

    Help!
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    Firstly, a transition metal is one which has at least one ion that has a partially filled d-orbital. As transition metal compounds have colours, this must have something to do with the d-orbital.
    In general, just like the flame tests, colours are formed due to the movement of electrons from to a higher energy level. In the case of transition metal colours, the colour is seen because the movement of an electron to a higher energy state absorbs some of the visible light. The colours that are NOT absorbed by the electron, are emitted- that's the colour we see.
    The colours form when there are ligands. Hence, the elements dont have a colour.
    When a ligand "bonds" to a transition metal ion, it causes the d-orbital-the 5 sub levels of the d-orbital- to split. This splitting depends on which ligand is present. That's why different colours are seen when transition metal compunds are disolved in different solvents.
    When the d-orbital splits, some of it is at a higher energy level than the rest of it. So an electron moves to the higher energy part of the orbital, absorbing some light as it moves. The colours of white light that the electron does not absorb is emitted by the solution, and is what we see.
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    (Original post by Dal)
    Firstly, a transition metal is one which has at least one ion that has a partially filled d-orbital. As transition metal compounds have colours, this must have something to do with the d-orbital.
    In general, just like the flame tests, colours are formed due to the movement of electrons from to a higher energy level. In the case of transition metal colours, the colour is seen because the movement of an electron to a higher energy state absorbs some of the visible light. The colours that are NOT absorbed by the electron, are emitted- that's the colour we see.
    The colours form when there are ligands. Hence, the elements dont have a colour.
    When a ligand "bonds" to a transition metal ion, it causes the d-orbital-the 5 sub levels of the d-orbital- to split. This splitting depends on which ligand is present. That's why different colours are seen when transition metal compunds are disolved in different solvents.
    When the d-orbital splits, some of it is at a higher energy level than the rest of it. So an electron moves to the higher energy part of the orbital, absorbing some light as it moves. The colours of white light that the electron does not absorb is emitted by the solution, and is what we see.
    Pretty good explanation but just a note of caution - no light is "emitted" this would imply some kind of fluorescence, in solutions the correct term is "transmitted" ie allowed to pass through. Some of the wavelengths are absorbed and the remainder are transmitted - we see the transmitted wavelengths. If we are dealing with solids, then some light is absorbed and the unaffected wavelengths reflected.
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    Thank u guys for providing such useful info.

    What i read in the book was "the transition complex which have the lowest absorption frequency for the spectrum is emitted". On the other hand it was written "we see a colour of blue region as the specturm absorbs the light in the red region."

    please also clarify me the above statements.

    Just incase, if u ppl dont know that the solution of Cu(I) and zinc(II) are colourless bcoz:
    1. as they ve 3d10 configuration the energy required to excite them is outside the visible region
    2. also, the 3d10 is full and there is no empty orbital for tranisition to take place.
 
 
 
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