Question

Which one of the following does not belong to the family of the alkali metals?(a) Li (b) Na (c) Be (d) K

Answer 1

Answer:

your answer for the question is Be

Answer 2

Answer:

Beryllium (Be) doesn’t belong to the family of the alkali metals. This is because;

• ‘Alkali metals’ like Li, Na, K belong to the Group 1A (have one electron in their outermost orbit) in the periodic table whereas Beryllium belongs to group 2A (‘two electrons’ in their outermost orbit ) which are called the alkaline earth metals.  
• Alkali metals like Li, Na, and K and “alkaline earth metals” when reacted with water, displaces $\mathrm{H}_{2}$  from water to form a basic solution; whereas alkaline earth metal Beryllium doesn’t react with water, due to its smaller atomic radius and “high ionization energy” “compared to other elements” of the same group.
• Similarly the alkali metal hydrides and the alkaline “metal hydrides” react with water to form metal hydroxide releasing hydrogen, however, beryllium is exceptional to these reactions.