1A Н 2A 0.31 8A 7A 3A 4A БА 6A He 0,28 Be 0.96 Li 1.28 Increasing radius Ne 0,84 0.76 0.71 0.66 0.57 0,58 Mg 1.41 Na 1.66 Si P. Al Ar 1.21 1.11 1.07 |1.05 1.02 1.06 Kr 60 1.53 1.39 1.391.32 |l.26 1.24 1.32 1.22 1.22 1.20 1.19 1,20 1.20 1.16 Cr Mn Fe Co Ni Cu Zn Ga Ti Ca Sc a K 2.03 Ge As Se Br Nb Mo Tc Ru Rh Pd Sr Y. Zr 1,95 190 1.75 1.64 1.54 147 1.46 1,42 1391451.44 1 42 139 1.39 1.38 1.39 1.40 Rb Ag Cd In Sn Sb Te 2.20 Xe Radius (Å) Increasing radius Figure 7.7 Trends in bonding atomic radii for periods 1 through 5.

Describe the molecular shape of the following:       (a) NCl2+

7.83 In the series of group 16 hydrides, of general formula MH2, the measured bond distances are 0-H, 96 pm; S-H, 134 pm; Se-H, 146 pm. (a) Compare these values with those estimated by use of the atomic radii in Figure 7.7. (b) Explain the steady increase in M-H bond dis- tance in this series in terms of the electron configurations of the M atoms.

The pentafluorides of the larger members of Group 5A(15)have been prepared, but N can have only eight electrons. A claim has been made that, at low temperatures, a compound with the empirical formula NF₅ forms. Draw a possible Lewis structure for this compound.