Diagonal Relationship Between Beryllium and Aluminium - Practice Questions & MCQ

The ionic radius of Be²⁺ is estimated to be 31 pm; the charge/radius ratio is nearly the same as that of the Al³⁺ ion. Hence beryllium resembles aluminium in some ways. Some of the similarities are:

• Like aluminium, beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal.
• Beryllium hydroxide dissolves in excess of alkali to give a beryllate ion, just as aluminium hydroxide gives aluminate ion, 
• The chlorides of both beryllium and aluminium have Cl^– bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong Lewis acids. They are used as Friedel Craft catalysts.
• Beryllium and aluminium ions have strong tendency to form complexes, BeF₄^2–, AlF₆^3–.