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Unformatted text preview: - - - 3+
Fe [Ar] 3d - - - 4s 3d +
Cu [Ar] 4s 0 3d 10 11 10
[Kr] 5s 0 4d Chemistry 101 Chapter 9 IONIC RADII Ionic Radius Ø is the radius of the spherical region around the nucleus within which the electrons are most likely to be found. Ø is obtained fro m known distances between nuclei in ionic crystals (obtained by Xray diffract ion crystallography, a method that makes the posit ions of the nuclei visible) Determining the Radius of the I - (iodide) ion in LiI (lithium iodide) · Distance between the nuclei of two I - ions = 426 pm 426 pm Radius of the I ion = ¾¾¾ = 213 pm 2
· From this informat ion the radius of the Li io n can be determined fro m the experimentally + determined distance between Li ion and the I - ion. d Radius of Li + = d (Li + I - ) – 213 pm 12 Chemistry 101 Chapter 9 RADII OF CATIONS > Radii of atoms Radii of Cations 0 Na 2 2 6 1s 2s 2p 3s1 +
Na 1s2 2s2 2p 6 3 shells 2 shells isoelectronic with Ne · Isoelectronic = species having the same number of electrons and electron configurat ion.
· Arrange the fo llowing species in order of increasing size: Fe 0 Fe 3+ Fe 2+ 26 p, 26 e 26 p, 23 e 26 p, 24 e 2 6 5 [Ar] 4s 3d [Ar] 3d [Ar] 3d 6 4 shells 3 shells 3 shells weaker interelectron repulsio ns smaller ion Fe 3+
smallest < Fe 2+ stronger interelectron repulsio ns larger ion < Fe 0 largest Conclusion:
· For cations of the same element (same number of protons): The larger the positive ionic charge, the smaller the ca...
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