Beryllium and magnesium do not give colour to flame whereas other alkaline eath metals do so. Why?

Explanation

Because of the small size , the ionization enthalpies of Be and Mg are much higher than those of other alkaline earth metals . Therefore , they need large amount of energy for excitation of their valence electrons to higher energy levels . Since such a large amount of energy is not available in Bunsen flame , therefore , these metals do not impart any colour to the flame .