Question

Why aluminium chloride forms covalent compound

Answer 1

• As Al has very high ionization energy and for Cl its not easy to withdraw 3 electrons from Al’s outer most shell because Cl is not enough electronegative

Therefore, Al rather loosing 3 electrons it shares its electrons with 3 Cl ions and when electrons shared with 2 atoms ; covalent bond is formed

● Fajan’s rule :- According to fajan’s rule , larger the size of anion ; more covalent will be the bond

So, if we take an example of AlCl3 and AlF3, here F ion is smaller then Cl ion ( as we know) also F is enough electronegative to withdraw Al outermost electrons and

Therefore AlF3 is ionic but AlCl3 is covalent

● Electronegativity difference:- If Electronegativity difference between bounding atoms is less than 1.7 then bond has more covalent charactor

And Electronegativity difference is 1.55 between Al and Cl

Therefore Al——Cl bond is covalent