What is the ground-state electronic configuration of halogens (Group VII A)?

Halogens are elements in Group VII A (17) of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine. Their chemical behavior and reactivity are largely determined by their valence electron configuration. In the ground state, halogens have the ns²p⁵ electronic configuration, where "n" represents the valence shell number. This means each halogen atom has seven valence electrons: two in the s-orbital and five in the p-orbital.

Having one electron less than a complete octet makes halogens highly electronegative and reactive. They readily gain one electron to achieve a stable noble gas configuration, forming halide ions (X⁻) in ionic compounds. The single unpaired electron in the p-orbital also allows halogens to participate in covalent bonding, forming molecules like Cl₂, F₂, and HCl.

Other options do not correspond to halogens:

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  ns²p² → Group IV A (e.g., carbon, silicon)

  
  


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  ns²p⁴ → Group VI A (chalcogens, e.g., oxygen, sulfur)

  
  


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  ns²p⁶ → Group VIII A (noble gases, e.g., neon, argon)

  
  

The ns²p⁵ configuration explains trends in reactivity, electronegativity, and their tendency to form single bonds with metals or hydrogen. It also accounts for their strong oxidizing nature and ability to form compounds with other nonmetals.

Understanding this configuration is fundamental in inorganic chemistry, as it helps predict chemical properties, bond formation, and the placement of halogens in the periodic table.

In summary, the ground-state electronic configuration of halogens is ns²p⁵, which defines their chemical behavior, high reactivity, and ability to achieve a stable octet through electron gain.