Assume that the packing of spherical atoms in crystalline metals is the same for Li, Na, and K, and explain why Na has a higher density than both Li and K. Use data from Table 21.2.

Table 21.2

 

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TABLE 21.2 Some Properties of the Group 1 (Alkali) Metals Li Atomic number Valence-shell electron configuration Atomic (metallic) radius, pm Ionic (M) radius, pmª Electronegativity Charge density of M+, C mm 3 First ionization energy, kJ mol-1 Electrode potential Eº, Vb Melting point, °C Boiling point, °C Density, g cm3 at 20 °C Hardness Electrical conductivityd Flame color Principal visible emission lines, nm 3 2s¹ 152 73 1.0 98 520.2 -3.040 180.54 1347 0.534 0.6 17.1 Carmine 610, 671 Na 11 3s¹ 186 116 0.9 24 495.8 -2.713 97.81 883.0 0.971 0.4 33.2 Yellow 589 K 19 4s¹ 227 152 0.8 11 418.8 -2.924 63.65 773.9 0.862 0.5 22.0 Violet 405, 767 Rb 37 5s¹ 248 166 0.8 8 403.0 -2.924 39.05 687.9 1.532 0.3 12.4 Bluish red 780, 795 Cs 5.5 6s¹ 265 181 0.8 6 375.7 -2.923 28.4 678.5 1.873 0.2 7.76 Blue 456, 459