GCEChemistryAtomic Structure and Periodicity2024

The electronic configuration of an element is 1s² 2s² 2p⁶ 3s² 3p³. Which of the following correctly describes this element?

AIt is a noble gas in Period 3
BIt has three unpaired electrons and belongs to Group VACORRECT
CIt has a completely filled p subshell
DIt is a metal with valency 2
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Why the answer is B, and why the others tempt you.
The configuration 1s² 2s² 2p⁶ 3s² 3p³ belongs to phosphorus (Z=15). The 3p³ subshell has three half-filled orbitals, giving three unpaired electrons. With five valence electrons (3s² 3p³), it belongs to Group VA of the periodic table.
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