Which orbital is filled immediately after the 4s orbital according to the Aufbau principle?
Correct answer: B. 3d
- A. 4p
- B. 3d
- C. 4d
- D. 5s
Explanation
Orbitals fill in order of increasing n plus l, and where that sum ties the lower n goes first. For 3d the sum is 5 and for 4p it is also 5, but 3d has the lower principal quantum number and so fills first, which is why the first transition series follows calcium. The 4p orbitals are filled only after the 3d subshell is complete at zinc.
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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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