Question

elements of group 17 are coloured.Why?

Answer 1

Due to D - D transition group 17 elements and colours.

Answer 2

Elements of group 17 are coloured because they are radioactive.

Explanation:

Group 17 in the modern periodic table is generally composed of the transitional elements. They are also termed as the halogens group. They are toxic and highly reactive. They are highly reactive because in their outermost orbit there are 7 electrons on each and as per the atomic property they try to gain an electron each on their last orbit an to be stabled as like the nearest noble gas.

The main reason behind colouring the series with different colours for each element because the show radiation. It is the highest energy region in the periodic table.  Since the amount of energy required for excitation differs for each halogen, each halogen displays a different colour. And they show radiation because they have the number of neutrons more than protons.