Discuss briefly the similarities between beryllium and aluminium

Explanation

Diagonal relationship:As observed in alkali metals, beryllium shows a diagonal relationship with aluminium. Similarities between beryllium and aluminium:
(1) Beryllium and aluminium have same electronegativity values.
(ii) Their changes per unit area is closer.
(iii) `BeCl_(2)`and `AICI_(3)` forms dimeric structure. Both are soluble in organic solvents and are strong Lewis acids.
(iv) `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. (v) Be and Al ions have strong tendency to form complexes. e.g. `BeF_(4)^(2-)` and `AIF_(6)^( 3-)`
(vi) Both `Be(OH)_(2))` and `Al(OH)_(3)` are amphoteric in nature
(vii) Carbide of Be - beryllium carbide `(Be_(2)C)` and Al-aluminium carbide `(Al_(4)C_(3))` give methane on hydrolysis
(viii) Both beryllium and aluminium are rendered passive by nitric acid.