Which electronic configuration corresponds to an element of group IIIA ?
Correct answer: B. 1s2 2s2 2p6 3s2 3p1
- A. 1s2 2s2 2p3
- B. 1s2 2s2 2p6 3s2 3p1
- C. 1s2 2s2 2p4
- D. 1s2 2s2 2p6 3s2 3p6 4s2 3d1
Explanation
Group IIIA, now called Group 13, elements have two electrons in the outer s subshell and one in the outer p subshell, giving the valence pattern ns2 np1. Option b has 3s2 3p1, whereas option d has 4s2 3d1 and represents a d-block configuration rather than Group IIIA.
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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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