Question

explain why Cu+ ion is not coloured??
plz explain in detail

Answer 1

D block elements of periodic table are called as Transition elements. Transition elements have partially filled d orbitals. The colour for the elements of D block is due to transition of electrons which is called as  d -Transition for which presence of partially filled d electrons is must.
copper  Cu , has 29 electrons.
so  electronic configuration will be 1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰
but in case of Cu+ ion, 28 electrons so:
electronic configuration will be 1s²2s²2p⁶3s²3p⁶3d¹⁰
Cu+ion will loose its 4s¹ electron,  and as it has filled 3d¹⁰ orbital,therefore no transition  and hence cu+ ion will not have any colour.