. Write the Characteristic of flame colours
The characteristic flame colour shown are : Ca-brick red; Sr –crimson ; Ba-apple green and Ra-crimson.
i. Alkaline earth metals except Be and Mg produce characteristic colour to flame due to easy excitation of electrons to higher energy levels.
ii. Be and Mg atoms due to their small size, bind their electrons more strongly (because of higher effective nuclear charge)
Hence these requires high excitation energy and are not excited by the energy of flame with the result that no flame colour is shown by them.