In trivalent oxidation state, most of the compounds are covalent and hence hydrolyzed in water. For example, the trichlorides form tetrahedral species on hydrolysis in water.
Explain how?
Dear Student,
Please find below the solution to the asked query.
As you know that according to Fajan's rules of covalency, smaller size of cation and higher charge has more covalent character. Thus, most of the compounds are covalent in their trivalent oxidation states. Take for an example of group 13 element, AlCl3. According to Fajan's rules, high charge density of Al3+ favours covalency. Thus, AlCl3 shows covalent character and it is still soluble in water. This is because of high hydration energy. Smaller the size of cation, larger is the hydration energy. Thus, as any element loses electrons, the size of its cation decreases. The large hydration energy of Al3+ results in vigorous exothermic reaction with water and forms acidic solution.
AlCl3 + 6H2O [Al(H2O)6]3+ + 3Cl-
Al(H2O)6]3+ + H2O → [Al(OH)(H2O)5]2+ + H3O+
Hope this information clears your doubt about this topic. In case of any other doubt, do ask here on the portal and our experts will try to help you out as soon as possible.
Regards
Akanksha Jain
Please find below the solution to the asked query.
As you know that according to Fajan's rules of covalency, smaller size of cation and higher charge has more covalent character. Thus, most of the compounds are covalent in their trivalent oxidation states. Take for an example of group 13 element, AlCl3. According to Fajan's rules, high charge density of Al3+ favours covalency. Thus, AlCl3 shows covalent character and it is still soluble in water. This is because of high hydration energy. Smaller the size of cation, larger is the hydration energy. Thus, as any element loses electrons, the size of its cation decreases. The large hydration energy of Al3+ results in vigorous exothermic reaction with water and forms acidic solution.
AlCl3 + 6H2O [Al(H2O)6]3+ + 3Cl-
Al(H2O)6]3+ + H2O → [Al(OH)(H2O)5]2+ + H3O+
Hope this information clears your doubt about this topic. In case of any other doubt, do ask here on the portal and our experts will try to help you out as soon as possible.
Regards
Akanksha Jain