Question

Give reasons for the following :
(a) Li+ resembles Mg 2+ .
(b) Alkali metals show characteristic colours in the flame

Answer 1

Answer:

a) Due to its small size, lithium differs from other alkali metals but resembles with Mg as its size and other periodic properties are closer to Mg. Its resemblance with Mg is known as diagonal relationship.

b) Alkali metals impart characteristic colours to the flame due to low ionisation enthalpy, when an alkali metal or its salt is heated in a flame, the valence electrons are excited to higher energy level.

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