Question

Discuss briefly the similarities between beryllium and aluminium.

Answer 1

Diagonal relationship: As observed in alkali metals, beryllium shows a diagonal relationship with aluminium.

Similarities between beryllium and aluminium:

1. Beryllium and aluminium have the same electronegativity values.
2. Their changes per unit area are closed.
3. BeCl₂ and AlCl₃ forms dimeric structure. Both are soluble in organic solvents and are strong Lewis acids.
4. Be(OH)₂ and Al(OH)₃ dissolves in excess alkali to give beryllate ion [Be(OH)₄]^2– and aluminate ion [Al(OH)₄]^–, respectively.
5. Be and Al ions have a strong tendency to form complexes, e.g. BeF₄^2– and AlF₆^3–
6. Both Be(OFI)₂ and Al(OH)₃ are amphoteric in nature.
7. Carbide of Be – beryllium carbide (Be₂C) and Al – aluminium carbide (Al₄C₃) give methane on hydrolysis.
8. Both beryllium and aluminium are rendered passive by nitric acid.