The correct electronic configuration of Cu is ___________________?
Correct answer: C. [Ar]3d104s1
- A. [Ar]4s1
- B. [Ar]4s2
- C. [Ar]3d104s1
- D. [Ar]3d94s2
Explanation
Copper has atomic number 29 and adopts the especially stable configuration [Ar]3d10 4s1, with a completely filled 3d subshell. It is an exception to the simple filling expectation [Ar]3d9 4s2 because one 4s electron shifts into 3d. Students may choose d by applying the basic Aufbau order without considering the extra stability of a filled d subshell.
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About Electronic Configuration
Electronic configuration describes how electrons occupy shells, subshells and orbitals around an atom. Questions use the Aufbau principle, Pauli exclusion principle and Hund's rule to write configurations, identify valence electrons, form ions and explain periodic trends, including common exceptions such as chromium and copper.
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