Question

discuss diagonal relationship between between beryllium and aluminum

Answer 1

(1) Be2+ and Al3+ have almost same and smaller size and thus favour for covalent bonding.

(2) Both these form covalent compounds having low melting point and soluble in organic solvent.

(3) Both have same value of electronegativity (which is 1.5).

4) The standard O.P of these elements are quite close to each other ; Be2+=1.69 volts and Al3+= 1.70 volts.

(5) Both become passive on treating with concentrated HNO3 in cold.      

(6) Both form many stable complexes for example (BeF3)-, (AlH4)-.  

(7) Like BeO, Al2O3 is amphoteric in nature. Also both are high melting point solids.          Al2O3 + 2NaOH → 2NaAlO2 + H2O          Al2O3 + 6HCl → 2AlCl3 + 3H2O  

Answer 2

Thanks for answering.   So much