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Ch 16. Group 16. O allotropes. O 2 : Ground state is a paramagnetic gas BP = -183 C (blue liquid) 3 / 2 O 2 (g) O 3 (g) Δ G f = +163 kJ/mol Ozone is a strong oxidant!. S allotropes. S: ring structures S 6 to S 20 with S 8 most common
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O allotropes O2: Ground state is a paramagnetic gas BP = -183 C (blue liquid) 3/2 O2 (g) O3(g) ΔGf = +163 kJ/mol Ozone is a strong oxidant!
S allotropes S: ring structures S6 to S20 with S8 most common S8 --> Sn (a red, viscous, elastomeric helical polymer) Sn is metastable at RT, reverts to S8 application: Na/S battery uses a molten S anode Na (liq) + Sn(liq) NaSn
HSO3F S8 + 3AsF5 (S8)(AsF6)2 + AsF3 bright red solution 4 Se + S2O6F2 (Se4)(SO3F)2 Se42+ is a square planar ring Elemental forms S-S ~ 0.19-0.21 nm transannular bond ~ 0.28 nm Se Te Po increasing metallic character Se (m) is a semiconductor, photoconductor, bandgap ~ 1.8 eV Po is metallic, primitive cubic structure, radioactive with max body burden = 7x1012g (20 trillion atoms) S82+
S halides C2
S halides C2v C2v
S halides Oh kinetically stable against hydrolysis
S oxides generally mild oxidants or mild reducing agents, i.e. they are readily oxidized or reduced “+2” S2O32 thiosulfate +4 SO2 weak LA C2v H2SO3 sulfurous acid SO32- (sulfite) C3v +6 SO3 strong LA D3n H2SO4 sulfuric acid SO42 (sulfate) Td Add BF3 to SO3 to prevent oligomerization
S oxides +6 S2O82 peroxydisulfate S2O82 2 SO4- . 2 SO42- 2e- , ~+2V
SN compounds (28 pp in Greenwood and Earnshaw, Chemistry of the Elements) S2N2 almost sq. planar S4N4 S4N4 (SN)x polysulfurnitride, zig-zag chain, metallic conduction in chain direction Δ, Ag SN compounds