Which of the following is not regarded as transition element ?

Question

Accepted Answer

Option 3, Zn (Zinc), is correctly identified as not being regarded as a transition element. Here's why:

1. **Explanation for Option 3 (Zn):**
   - Transition elements are defined as those elements that have partially filled d orbitals. Zinc, with the electronic configuration [Ar] 3d^10 4s^2, has a completely filled d subshell. In both its elemental form and its common oxidation state (+2), the d orbitals remain fully filled. Therefore, it does not meet the criteria of having partially filled d orbitals, which is a characteristic feature of transition elements. This makes Zn not a transition element.

2. **Explanation for why other options are incorrect:**

- **Option 1 (Zr - Zirconium):**
     - Zirconium has the electronic configuration [Kr] 4d^2 5s^2. It has partially filled d orbitals, which qualifies it as a transition element. In its common oxidation states, the d orbitals are not completely filled, aligning with the definition of transition elements.

- **Option 2 (Cu - Copper):**
     - Copper has the electronic configuration [Ar] 3d^10 4s^1. Although in its elemental form the d orbitals are fully filled, copper commonly exhibits a +2 oxidation state, where the configuration becomes [Ar] 3d^9, resulting in partially filled d orbitals. This characteristic makes copper a transition element.

- **Option 4 (Ni - Nickel):**
     - Nickel has the electronic configuration [Ar] 3d^8 4s^2. It has partially filled d orbitals in its elemental state and in its common oxidation states, which is a defining feature of transition elements. Therefore, nickel is considered a transition element.

In summary, Zinc (Zn) is not regarded as a transition element because it does not have partially filled d orbitals in its common oxidation states, unlike the other elements listed.