Chapter 15 Group 15 Elements Occurrence and extraction Physical Properties Metals Halides, oxides, hydroxides, salts of oxoacids Phosphoacids Sulfides and selenides 1 http://www.cpsc.gov//PageFiles/122137/270.pdf http://www.semiconductor-today.com/news_items/2012/APRIL/YOLE_170412.html Relative abundances of the group The main components (by percentage 15 elements in the Earth’s crust. volume) of the Earth’s atmosphere 2 Phosphorus containing nerve agents. Destruction of the nerve agents Selected low-temperature baths involving liquid N2. 3 covalent bond enthalpy terms (kJ mol1) vs. 4 Schematic representation of the electronic repulsion, believed to weaken the FF bond in F2. Composition of air N2 - dinitrogen Methods to produce Fractional distillation N2 on a small scale Membrane separation http://www.mvsengg.com/products/nitr http://www.bbc.co.uk/schools/gcsebites ogen/membranenitrogen/membrane_pr ize/science/edexcel_pre_2011/oneearth/ ocess_detail/ usefulproductsrev2.shtml 5 Phosphorus tetrahedral P4 Part of one of the chain- like arrays of atoms present in the infinite http://en.wikipedia.org/wiki/File:PhosphComby.jpg lattice of Hittorf’s phosphorus http://en.wikipedia.org/wiki/File:PhosphorusAllotropes.svg Part of one layer of puckered 6-membered rings present in black phosphorus Arsenic, antimony, and Arsenic bismuth in the solid state Vapor phase 4M + 3O2 2M2O3 (M = As, Sb, Bi) 2As + 6NaOH 2Na3AsO3 + 3H2 6 http://www.yetterco.com/media-library/videos/preview/12.jpg 7 Chemistry of ammonia (NH3) barrier to inversion is low, 24 kJ mol-1 4NH + 3O 2N + 6H 3 2 2 2 Oxidation products depend on conditions 4NH3 + 5O2 ––Pt/Rh 4NO + 6H2O + - -5 NH3(aq) + H2O(l) ⇌ [NH4] (aq) + [OH] (aq) Kb = 1.8x10 + + -10 [NH4] (aq) + H2O(l) ⇌ [H3O] (aq) + NH3(aq) Ka = 5.6x10 NH3 + HBr NH4Br CaSO4 + 2NH3 + CO2 + H2O CaCO3 + [NH4]2SO4 NH3 + HNO3 NH4NO3 Chemistry of phosphine/phosphane (PH3) liquid NH3 + - K + PH3 K + [PH2] + 1/2H2 HX + PH3 PH4X + + [PH4] + H2O PH3 + [H3O] PH3 acts as a Lewis base, forms a range of adducts: H3B·PH3Cl3B·PH3 Ni(PH3)4 Ni(PH3)2(CO)2 PH3 + 2O2 --Δ H3PO4 8 Hydrides E2H4 (E = N, P, As) NH3 + NaOCl NH2Cl + NaOH fast NH3 + NH2Cl + NaOH N2H4 + NaCl + H2O slow Hydrazine (N2H4) is kinetically stable with respect to N2 and H2. -1 ΔfH(298K) = +50.6 kJ mol Removes O2 from industrial boilers (forms N2H4 + O2 N2 + 2H2O) Alkyl derivatives used with N2O4 as rocket fuel. (a) The structure of N2H4, and Newman projections showing (b) the observed gauche conformation, and (c) the possible staggered conformation. An eclipsed conformation is also possible. High Energy Density Materials 5,5'-azotetrazolate dianion Ba2+ (2+) + [N2H5]2[SO4] [N2H5]2 ·2H2O 373 K, in vacuo (2+) (2+) [N2H5]2 ·2H2O [N2H5]2 ΔfH(s, 298 K) = +858 kJ/mol (3.7 kJ/g) 9 2- [P3H3] Potential diagram for nitrogen at pH = 0. Latimer (or reduction potential diagrams) show the standard reduction potentials connecting various oxidation states of an element. + Is hydroxlamine [NH3OH] stable with respect to disproportionation + + to N2 and [N2H5] & [NH4] ? 10 HN3 [N3] [PPh4][N3] + Me3SiN3 + EtOH [PPh4][N3HN3] + Me3SiOEt [N3HN3] 11 Metal and non-metal azide compounds 2- trans- [Ru(en)2(N2)(N3)] [Sn(N3)6] (i) Liquid HF, 195 K N2 : isolated 1790 (ii) Warm to 298 K - [N F]+[SbF ] + HN [N ]+[SbF ]- + HF N3 : synthesized 1890 2 6 3 5 6 + N5 : synthesized 1999 + - [NO] [SbF6] + 2.5N2 NO NO + - 2 + - [N5] [SbF6] [NO2] [SbF6] + 2.5N2 Br2 + - [Br2] [SbF6] + 2.5N2 12 Nitrides: titanium nitride coated saw blades Li3N, Na3N, Be3N2, Mg3N2, Ca3N2, Ba3N2 and AlN. •Hydrolysis of saline hydrides liberates NH3 •Na3N is hygroscopic Na3N + 3H2O 3NaOH + NH3 •Nitrides of d-block metals are hard, inert solids with high melting points and electrical conductivities. 2- Pernitrides [N2] are known for Sr, Ba. •Conditions of 5600 bar of N2 at 920 K for BaN2. Si3N4 are used in glow plugs. Phosphides Most elements (except Hg, Pb, As, Te) combine with P to form phosphides • Variety of solid state structures • Phosphides with d-block metals tend to be inert, metallic looking, with high melting point and electrical conductivities. • Group 1 metals form M3P and Group 2 metals form M3P2 • Are hydrolyzed by water and can be considered http://pubs.rsc.org/en/conten t/articlelanding/2010/cs/b916 ionic 787k#!divAbstract • The alkali metals can also form phosphides which contain groups of 3- 3- P atoms (e.g. [P7] and [P11] ) as chains or cages. 13 Gallium Arsenide • Important group III-V semiconductor that crystallizes with zinc-blende structure • Band gap of 1.42 eV, thus can be used to make devices that emit light in the infrared region. • Exhibits high electron mobility, 8500 cm2V-1s-1 vs. silicon 1500 cm2V-1s-1 • Disadvantages of GaAs vs Si: • Expensive • Brittle • Lower Thermal Conductivity • Highest-efficiency single-junction solar cell at 28.8% • http://dx.doi.org/10.1109%2FPVSC.2012.6317891 NiAs (nickel arsenide) Ni As Unit cell of NiAs 14 [Sb ]2 or [Bi ]2 Pd-centered pentagonal 8 8 antiprismatic structure of 4 [Pd@Bi10] 15 Selected reactions of PCl5. {SbF5}4 [Sb2F11] 2 [As6I8] 16 [BiCl3(15-crown-5)] [BiCl3L] Oxides of Nitrogen 17 2- [N2O2] 18 HNO3 - NO3 19 oxoacids of phosphorus 20 4 [W3(OH2)9NiSe4{PH(OH)2}] 21 enantiomers (non-superimposable mirror images) unit cell of FeSb2O6 unit cell of NaSbO3 22 [Cl3PNPCl2NPCl3] Proposed reaction scheme for the formation of the cyclic [Cl3PN(PCl2N)2PCl3] phosphazene (NPCl2)3 phosphazenes (NPX2)3 P4N4 ring conformations + N- P P+ N- P+ N- 23 2 (R)-[Sb(O2CCF3)3] Bi2(O2CCF3)4 [Bi2(C6H4O2)4] 24.