Question

consider the halogens Cl2, Br2, I2.
(I) state the trend in their colour intensity.
(ii) (a) state the trend in volatility of the elements.
(b) account for this trend in volatility, in terms of atomic size and inter-molecular bonding

Answer 1

intensity of color increases as you go from Cl2, to Br2, to I2
the volatility decreases as you go down the group, so Cl2>Br2>I2
because intermolecular bonding and atomic sizes increase as you go down the group, increasing the atom's stability and decreasing the volatility.