Which pair of transition elements shows abnormal electronic configuration?
Correct answer: D. Cu and Cr
- A. Sc and Zn
- B. Cu and Sc
- C. Zn and Cu
- D. Cu and Cr
Explanation
Both Cu and Cr show abnormal electronic configurations.Cu (Copper) has the electronic configuration of [Ar] 3d10 4s1 instead of [Ar] 3d9 4s2. This is because a filled d-subshell (d10) and a half-filled s-subshell (4s1) are more stable configurations than a partially filled d-subshell (d9) and a filled s-subshell (4s2).Cr (Chromium) has the electronic configuration of [Ar] 3d5 4s1 instead of [Ar] 3d4 4s2. This is because a half-filled d-subshell (d5) is more stable than a partially filled d-subshell (d4) due to the exchange energy.
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About Transition Elements
Transition elements are identified by their partially filled d subshells in atoms or common ions. The topic covers the electronic structure of d-block elements, including the filling order of 4s and 3d orbitals, variable oxidation states and the distinction between transition elements and elements with completely filled d subshells.
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