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The elements in group 15 Nitrogen Phosphorus Arsenic Antimony Bismuth

The elements in group 15 Nitrogen Phosphorus Arsenic Antimony Bismuth. Introduction. All are important elements Increasing trend to metallic character and cationic behavior from top to botom in the grroup Nitrogen is different with the other elements, even phosphorus

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The elements in group 15 Nitrogen Phosphorus Arsenic Antimony Bismuth

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  1. The elements in group 15 Nitrogen Phosphorus Arsenic Antimony Bismuth

  2. Introduction • All are important elements • Increasing trend to metallic character and cationic behavior from top to botom in the grroup • Nitrogen is different with the other elements, even phosphorus • The diminished ability to form p-p π bond: radius, single bond • The possibility of utilizing the d orbitals: d-p π bond , CN

  3. Introduction (continue) • All , but Bi, are important donor atoms in their trivalent compounds • Bismuth is a metal element, but sodium bismuthate is a very strong oxidizing agent: inert electron pair effect

  4. Ca5(PO4)3F(s) + H2SO4(I) 3H3PO4(l) + 5CaSO4(s) + HF(aq) 2Ca3(PO4)2 + 6SiO2 + 10C 6CaSiO3 + 10CO + P4 1500 °C Occurrence and Recovery of the Elements Phosphorus Principally obtained from phosphate rock -remains of fossilized life forms Ca5(PO4)3F and Ca5(PO4)3OH

  5. Elemental Phosphorus White Phosphorus Black Phosphorus • White Phosphorus: • Reaction on previous slide • Ignites spontaneously in air • Stored under water • Red Phosphorus: • Heat white phosphorus at • 300 C in inert atm for several days • Does not ignite in air • Structure: contain linear chain • Black Phosphorus • The most stable form • Formed when P heated under high pressure.

  6. Occurrence and Recovery of the Elements Arsenic is made on an industrial scale by heating appropriate minerals in the absence of air. The arsenic is condensed out as a solid. FeAsS (700°C)      FeS + As(g) +   As(s) Arsenic Arsenic is found in nature in a number of minerals including realgar (As4S4) orpiment (As2S3) arsenolite (As2O3) iron minerals such as arsenopyrite (FeAsS) loallingite (FeAs2).

  7. Occurrence and Recovery of the Elements Antimony is found in nature in a number of minerals including stibnite (Sb2S3) ullmanite (NiSbS). Small amounts of native antimony have been found. Some ores are treatable under reducing conditions to form Sb2S3. The sulphide is removed to leave elemental antimony with scrap iron. Sb2S3 + 3Fe      2Sb + 3FeS In antehr process, some ores can be heated to evolve the oxide Sb2O3 and this in turn can be reduced by charcoal in the presence of sodium sulphate, to ensure mixing, to form elemental antimony. 2Sb2O3 +3C     4Sb + 3CO2 Antimony

  8. Occurrence and Recovery of the Elements Bismuth Bismuth is found in nature largely as bismite (Bi2O3) bismuthinite (Bi2S3) bismutite [(BiO)2CO3]. However it is generally made as a byproduct of copper, lead,tin, silver, gold, and zinc plants. The final step involves a reduction of the oxide by charcoal.

  9. Phosphine PH3 Typically prepared by the action of dilute acid on calcium or aluminum phosphide or by pyrolysis of H3PO3 or by reaction of KOH on white phosphorus Pure phosphine is not spontaneously flammable but often inflames due to the presence of trace P2H4 or P4 • Readily oxidized by air once ignited • Sparingly soluble in water • Very weak base pKb 1E-25 PH4+ is readily hydrolized Extremely poisonous Only phosphine of the lower Group 15 elements forms subhydrides - P2H4 Used as a semiconductor dopant source

  10. Arsine AsH3 Even more poisonous than phosphine Readily decomposes to yeild elemental arsenic -”arsenic mirror test” Only know use as a semiconductor dopant source • Stibine SbH3 and Bismuthine BiH3 • Limited stability makes these compounds of little interest • Bond energy (stability): NH3 >PH3 >AsH3 >SbH3 >BiH3 • Bond angle (HAH): NH3 >PH3 >AsH3 >SbH3 >BiH3 • Base strength in water: same as above • Reduce ability: NH3 <PH3 <AsH3 <SbH3 <BiH3

  11. colourless gas • Melting point: -152°C • Boiling point: -102°C PF3 • colourless gas • Melting point: -86.5 • Boiling point: -6.2 P2F4 • colourless gas • Melting point: -94°C • Boiling point: -85°C PF5 2PCl3(l) + 3ZnF2(s) 2PF3(g) + 3ZnCl2(s) Compounds of Group 15 Elements Halides: PX3 PX5 Phosphorus Fluorides

  12. colourless liquid • Melting point: -6°C • Boiling point: 63°C AsF3 AsF5 • colourless gas • Melting point: -79.8°C • Boiling point: -52.8°C Compounds of Group 15 Elements Halides: Arsenic Fluorides “Bridged” structure, but essentially molecular

  13. AsCl5 AsCl3 Decomp at –50 °C Recall BrO4– • Colourless liquid • Melting point: -16°C • Boiling point: 130°C AsBr3 white to pale yellow crystalline solid Melting point: 31°C Boiling point: 221°C AsI3 • red crystalline solid • Melting point: 141°C • Boiling point: 400°C; 424°C Compounds of Group 15 Elements Other Halides

  14. colourless crystalline solid • Melting point: 290°C • Boiling point: 345°C SbF3 SbF5 • viscous liquid • Melting point: 8.3°C • Boiling point: 141°C Compounds of Group 15 Elements Halides: Antimony Fluorides Actual structure has intermolecular contacts giving highly distorted octahedral coordination Forms tetrameric structure in the solid state AsF3 and SbF3 are very useful as fluorinating agents

  15. colourless or yellow liquid • Melting point: 4°C • Boiling point: 140°C • Why liquid when trichloride a solid? SbCl5 SbCl3 • white crystalline solid, deliquescent • Melting point: 73.4°C • Boiling point: 223°C SbBr3 • white or yellow solid, deliquescent crystals • Melting point: 96°C • Boiling point: 288°C SbI3 • red crystalline solid • Melting point: 170.5°C • Boiling point: 401°C Compounds of Group 15 Elements Other Halides

  16. grey-white crystalline solid • Melting point: 649°C • Boiling point: 900°C BiF3 Ionic lattice BiF5 • white crystalline solid • Melting point: 154°C • Boiling point: 230°C Infinite linear BiF6 chains Compounds of Group 15 Elements Halides: Bismuth Fluorides What do the m.p. and b.p. imply? What do these m.p. and b.p imply?

  17. Nonexistant BiCl5 BiCl3 • white or yellowish white crystalline solid, • Melting point: 233.5°C • Boiling point: 441°C BiBr3 • yellow, golden crystalline solid, deliquescent • Melting point: 219°C • Boiling point: 462°C BiI3 • green-black crystalline solid • Melting point: 408.6°C • Boiling point: 542°C Compounds of Group 15 Elements Other Halides Bismuth Bromide Structure

  18. RCOCl + H3PO3 Cl3P=NPCl2O HCl + H3PO3 + H4P2O5 N2O4 Cl3PS RCO2H H2O P(NCO)3 P(NCS)3 AgNCO AgSCN R3PO S RMgX RMgX, LiR PR3, PR2Cl, PRCl Cl3PO O2 ROH (RO)2PO ROH RH + O2 P(OR)3 in base (RO)2PHO in absence of base Ni(CO)4 RCl + AlCl3 RPOCl2 + HCl NH3 [RPCl3]+[AlCl4]- Ni(PCl3)4 H2O P(NH2)3 RPOCl2 Reactions of PCl3 PCl3 Reactions of other MX3 Halides similar

  19. P4 + 5O2 P4O10 P4 + 3O2 P4O6 P4O10 + 6H2O 4H3PO4 P4O6 + 6H2O 4H3PO3 Oxides of P, As, Sb and Bi P4O10 a good drying and detergent agent Prepared by burning P in air Limit the supply of oxygen and: How to make an acid

  20. Oxides of Arsenic, Antimony and Bismuth Only As and Sb for (V) oxides, these are of limited stability. As, Sb and Bi oxides primarily (III) oxides As2O3 Sb2O3 Bi2O3 Note: Acid-base property Oxide-reduce property Gas Phase of As and Sb oxides:

  21. Sulphide • P4S3 P4S5 P4S7 P4S10… similar as oxides • Exclude P4S10, all contain at least one P–P bond • As2S3 As2S5 As4S4 … • Sb2S3 Sb2S5 • Bi2S3 why ? • Note: • Color: yellow to black. polarization covalent • Solubility and oxidizing-reduce properties • Reaction with H+, OH–, S2–, Sx2–

  22. H O H O O O O O P P P P P P P O O O O O O O H O O O O O O O O O Phosphorus Oxoanions:

  23. Structure and acidic strength of H3PO3 • Pauling rule: • HnROm: represented as ROm-n(OH)n • pK = 7 – 5(m – n) • In same type: electronegativity • Application: 1. H3PO3 P(OH)3 pK = 7 • Experimental: pK = 2 • H3PO3 HPO(OH)2 • P(OR)3

  24. Poly- and cycle-phosphoric acid(pyrophasphoric acid) • [PnO3n+1](n+2)– Ex. Na5P3O10 • [PnO3n]n– • Ex. Na5P3O9 • Note: • Solubilities of different phasphorates • Reducing properties of Hypo-/phosphite

  25. R R R P R PCl5 + nNH4Cl (Cl2PN)n + 4nHCl N N N R R N P P N N P (Cl2PN)n + 2nCF3CF2O- [(CF3CF2O)2PN]n + 2nCl- Phosphorus Nitrogen Compounds The extra valence in N can make for some interesting structures - Phosphazenes Substitutions by other Lewis bases are common Polymeric structures common – rubber-like substances -excellent low temperature properties

  26. planar N sp2, P sp3 d-p π May form polylimer Hexachlorotriphosphazene

  27. Complexes • PF6– AsF6– SbF6– • NaSb(OH)6 • KH[Sb2(d-C4H2O6)2] • Common for Bi3+ • Bi6O66+ Bi6O6(OH)33+Bi6O6(OH)6

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