The radii of F, F-,O and O2- are in the order of:

Correct answer: D. O2-> F- >O>F

  • A. O2->F-> F>O
  • B. F->O2-> F>O
  • C. O2->O>F->F
  • D. O2-> F- >O>F

Explanation

The order of ionic radii is determined by electron configuration and nuclear charge. For isoelectronic series, the size decreases with increasing atomic number due to greater effective nuclear charge. Anions are larger than their parent atoms because gaining electrons increases electron-electron repulsion. Therefore, O2- is the largest as it gains two electrons, followed by F- which gains one electron, neutral O, and then neutral F which is smallest due to the highest effective nuclear charge. Option D correctly reflects this order.

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Periodic properties arise from electron configuration and effective nuclear charge, producing trends in atomic and ionic radius, ionization energy, electron affinity, electronegativity, metallic character and reactivity. Comparisons run across periods and down groups, with attention to common exceptions. The topic also relates these trends to the behavior of s-block and p-block elements.

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