What is the oxidation state of Cadmium (Cd) in most compounds?

What is the oxidation state of Cadmium (Cd) in most compounds?

• A. +1
• B. +3
• C. 0
• D. +2

Answer: (D)

Cadmium’s outer electrons are 5s2, and it forms a very stable configuration by losing those two electrons to become Cd2+. That leaves a closed-shell [Kr] 4d10 arrangement, which is energetically favorable and makes the +2 oxidation state the dominant one in most compounds. In common Cd compounds like CdO, CdCl2, and CdSO4, cadmium appears as Cd2+, balancing the anions’ charges. Trying to form Cd+ would not provide the same stability, and forming Cd3+ would require removing electrons from a filled d shell, which is highly unfavorable. Hence the usual oxidation state of cadmium in compounds is +2.

Cadmium’s outer electrons are 5s2, and it forms a very stable configuration by losing those two electrons to become Cd2+. That leaves a closed-shell [Kr] 4d10 arrangement, which is energetically favorable and makes the +2 oxidation state the dominant one in most compounds. In common Cd compounds like CdO, CdCl2, and CdSO4, cadmium appears as Cd2+, balancing the anions’ charges. Trying to form Cd+ would not provide the same stability, and forming Cd3+ would require removing electrons from a filled d shell, which is highly unfavorable. Hence the usual oxidation state of cadmium in compounds is +2.