Question

The electronic configuration of Cu(II) is 3d9 whereas that of Cu(I) is 3d10. Which of the following is correct ?

• A. Cu(II) is less stable
• B. Stability of Cu(I) and Cu(II) depends on nature of copper salts
• C. Cu(II) is more stable
• D. Cu(I) and Cu(II) are equally stable

Answer 1

Answer: (C)

Cu(II) is more stable

Answer 2

• The stability of Cu(II) arises because it has a partially filled d -subshell ($3d^9$), which allows it to participate in ligand bonding and form complexes more effectively.
  • Cu(I) with $3d^{10}$ is more stable in certain cases due to the completely filled d -subshell, but Cu(II) is generally more stable in aqueous solutions.
  • The higher stability of Cu(II) over Cu(I) in aqueous medium is attributed to the higher hydration enthalpy of Cu(II) ions.