why halogens are colour ?
Dear user,
What Rahul has written is correct. Along with that answer, you must also note that all the halogens possess a valence shell electronic configuration s2,p5. This means that they contain unpaired electrons in their outermost p-orbital. These electrons absorb light and get promoted to higher orbitals. When they return to their ground state, they emit radiations which fall in the visible region of electromagnetic spectrum. Hence, they appear as coloured.
@Rahul, Good effort! Your answers are really helpful to all the users of this community. Keep writing!!!
Best wishes!!