1. Ch 16. Group 16

2. 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!

3. Na (liq) + Sn(liq)  NaSn
S allotropes
S: ring structures S6 to S20 with S8 most common
S > 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

4. Elemental forms S82+ S8 + 3AsF5  (S8)(AsF6)2 + AsF3
bright red solution
4 Se + S2O6F2  (Se4)(SO3F)2
Se42+ is a square planar ring
HSO3F
S-S ~ 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 = 7x1012g (20 trillion atoms)
S82+

5. S halides C2

6. S halides
C2v
C2v

7. S halides Oh
kinetically stable against hydrolysis

8. Frost diagrams

9. 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

10. S oxides +6 S2O82 peroxydisulfate S2O82  2 SO4- .  2 SO42-
2e- , ~+2V

11. Pourbaix diagrams

12. SN compounds
SN compounds (28 pp in Greenwood and Earnshaw, Chemistry of the Elements)
S2N2 almost sq. planar
S4N4
S4N  (SN)x polysulfurnitride, zig-zag chain, metallic conduction in chain direction
Δ, Ag