Zn, Cd, Hg, and Cn are not considered transition elements as their d orbitals are completely filled in both the ground state and common oxidation states, deviating from the characteristic incompletely filled d orbitals of transition elements.
Why are Zn, Cd, Hg, and Cn not regarded as transition elements despite having the electronic configuration (n-1)d¹⁰ ns²?
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Zinc (Zn), Cadmium (Cd), Mercury (Hg), and Copernicium (Cn) are not regarded as transition elements despite having the electronic configuration (n-1)d¹⁰ ns² because they do not exhibit the characteristic properties associated with transition metals. Transition elements are defined by their incomplete d subshells in the neutral atom or ions. However, Zn, Cd, and Hg of Group 12 have full d¹⁰ configurations in their ground state and common oxidation states, lacking partially filled d orbitals. Therefore, they do not display the typical behavior of transition metals. While Cn theoretically fits the electronic configuration, its properties are not well-studied due to its synthetic and highly unstable nature.