Electronic Configuration of Calcium (Ca) atom may be written as________?
Correct answer: B. Ar, 4s2
- A. Ne, 4p2
- B. Ar, 4s2
- C. Ne, 4s2
- D. Kr,4p2
Explanation
Calcium has atomic number 20, and the preceding noble gas is argon, atomic number 18; its remaining two electrons occupy 4s, giving [Ar] 4s2. The likely mistake is choosing [Ne] 4s2, which accounts for only 12 electrons and omits the filled 3s and 3p subshells.
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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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