Question

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

Answer 1

Whenan alkaline earth metal is heated, thevalence electrons get excited to a higher energy level. When thisexcited electron comes back to its lower energy level, it radiatesenergy, which belongs to the visible region. Hence, the colour isobserved. In Be and Mg, the electrons are strongly bound. The energyrequired to excite these electrons is very high. Therefore, when theelectron reverts back to its original position, the energy releaseddoes not fall in the visible region. Hence, no colour in the flame isseen.