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Chemistry of the Non-Metallic Elements

Valentim M. B. Nunes Engineering Unit – Chemistry Section April 2018. Chemistry of the Non-Metallic Elements. Non-metallic elements. The chemistry of these elements is very diverse. Some of them are considered metalloids as they show chemical properties of the metals and non-metals.

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Chemistry of the Non-Metallic Elements

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  1. Valentim M. B. Nunes Engineering Unit – Chemistry Section April 2018 Chemistry of the Non-Metallic Elements

  2. Non-metallic elements The chemistry of these elements is very diverse. Some of them are considered metalloids as they show chemical properties of the metals and non-metals.

  3. General Properties Hydrogen, H2, oxygen, O2, nitrogen, N2, fluorine, F2 and chlorine , Cl2 are gases at room temperature (and also the noble gases) Bromine, Br2, is a liquid. All the other elements are solids. Contrarily to metals, they are weak heat and electrical conductors. The oxidation states can be positive or negative. They are more electronegative elements than metals. The compounds formed between metallic elements and non metallic elements tend to be ionic.

  4. Hydrogen Is the more simple of all the elements. Its the more abundant element in the Universe (~70%), although he doesn't exist in Earth atmosphere. Isotopes: In the elementary form its a diatomic molecule, H2 (odorless and colorless gas and non-toxic) Resembles the alkali metals, in the sense that is easily oxidized to H+, but also the halogens as it forms the hydride ion, H-.

  5. Central Position in the Periodic Table? Many years ago in the now classic textbook College Chemistry (W.H. Freeman & Co., 1954), Linus Pauling placed the symbols for hydrogen and helium at the head and center of the periodic table We believe an adaptation in which hydrogen is centered at the head of the periodic table has great merit (see figure) and raise this proposal for consideration and adoption by IUPAC. Herb Kaesz and Peter Atkins, Chemistry International, 25(6), 14 (2003)

  6. Obtaining, reactions and applications Hydrogen is obtained industrially from the reaction between propane and water vapor in the presence of a catalyzer: C3H8(g) + H2O(g)  3 CO(g) + 7 H2(g) Ionic hydrides*: 2 Li(s) + H2(g)  2 LiH(s) Ca(s) + H2(g)  CaH2(s) H-(aq) + H2O(l)  OH-(aq) + H2(g) Covalent hydrides*: CH4, NH3, (BeH2)x, etc.. Interstitial hydrides*: TiH1.8, TiH2, etc... Applications: alimentary industry (hydrogenation of vegetable oils containing polyunsaturated molecules), fuel cells etc. * See figure 21.3 of the Chang book.

  7. Carbon Element essential to life. It forms long chains giving origin to billions of organic compounds. Occurs in non combined form as graphite or diamond (carbon allotropes) and also in natural gas , crude oil or coal (fossil plants)

  8. Inorganic reactions and applications Carbides : CaC2, Be2C C22-(aq) + 2 H2O(l)  2 OH-(aq) + C2H2(g) C4-(aq) + 4 H2O(l)  4 OH-(aq) + CH4(g) Cyanides: HCN NaCN(s) + HCl(aq)  NaCl(aq) + HCN(aq) Carbon oxides: CO, CO2 2 C(s) + O2(g)  2 CO(g) 2 CO(g) + O2(g)  2 CO2(g) Applications: Graphite (lubrication, pencils, ...), Cyanides (gold and silver extraction), carbon dioxide (refrigerants, extinctors, production of NaHCO3), etc..

  9. Nitrogen Its about 78% of the volume in air. Its an essential element for life (constituent of proteins and nuclear acids). Occurrence : KNO3 (salitre) and NaNO3 (Chile nitrate ) Obtaining: fractional distillation of air (boiling point of liquid nitrogen is about - 196 °C)

  10. Reactions and applications Nitrides: 6 Li(s) + N2(g)  2 Li3N(s) N3-(aq) + 3 H2O(l)  NH3(g) + 3 OH-(aq) Ammonia: N2(g) + 3 H2(g)  2 NH3(g) NH4Cl(aq) + NaOH(aq)  NaCl(aq) + H2O(l) + NH3(g) Hydrazine: N2H4(l) + O2(g)  N2(g) + 2 H2O(l) Oxides and Oxoacids: NH4NO3 (270 ºC)  N2O(g) + 2 H2O(l) N2(g) + O2(g)  2 NO(g) 2 NO(g) + O2(g)  2 NO2(g) Applications: ammonia (fertilizers), hydrazine (polymers, production of pesticides,..), nitrous oxide (analgesic), nitrous acid (fertilizers, dyes, medicines, explosives,...)

  11. Phosphorus The chemistry is similar to nitrogen. The allotropic forms are white phosphorous, P4 and red phosphorous, (P4)n. Occurrence: Ca3(PO4)2 (calcium phosphate) and Ca5(PO4)3F (fluoroapatite) Obtaining: 2 Ca3(PO4)2(s) + 10 C(s) + 6 SiO2(s)  6 CaSiO3(s) + 10 CO(g) + P4(s)

  12. Reactions and applications Phosphine, PH3: P4(s) + 3 NaOH(aq) + 3 H2O(l)  3 NaH2PO2(aq) + PH3(g) PH3(g) + 2 O2(g)  H3PO4(g) Halides of phosphorus: P4(l) + 6 Cl2(g)  4 PCl3(l) PCl3(l) + 3 H2O(l)  H3PO3(aq) + 3 HCl(g) PCl3(l) + Cl2(g)  PCl5(s) Oxides and oxoacids: P4(s) + 3 O2(g)  P4O6(s) P4(s) + 5 O2(g)  P4O10(s) P4O10(s) + 6 H2O(g)  4 H3PO4(aq) Ca3(PO4)2(s) + H2SO4(aq)  2 H3PO4(aq) + 3 CaSO4(s) Applications: white phosphorous(incendiary bombs, grenades), phosphoric acid and phosphates (detergents, fertilizers, toothpaste, buffer for carbonated drinks,...).

  13. Oxygen Its the most abundant element of the Earth's crust (~ 46%). Constitutes 21% in volume of the atmosphere. It is a colorless and odorless gas essential for life. Obtaining: industrially by the fractional distillation of liquefied air (boiling point of liquid oxygen ~ - 183 ºC)

  14. Reactions and applications Oxides, peroxides and superoxide's: O2-(aq) + H2O(l)  2 OH-(aq) O22-(aq) + 2 H2O(l)  O2(g) + 4 OH-(aq) 4 O2-(aq) + 2 H2O(l)  3 O2(g) + 4 OH-(aq) BaO2.8H2O(s) + H2SO4(aq)  BaSO4(s) + H2O2(aq) + 8 H2O(l) Ozone: 3 O2(g)  2 O3 (g) Applications: Oxygen (steel industry, sewage treatment , paper bleaching, Oxo acetylene, medicine, ...), peroxide of hydrogen (antiseptic, textile bleaching, hair, ...), ozone (water purification, deodorizing, bleaching, ...)

  15. Sulfur The most stable form is S8. It can assume several oxidations states. Occurrence: in elementary form; CaSO4.2 H2O (plaster), FeS (pyrite). Obtaining: extraction from subterraneous deposits by the Frasch method.

  16. Reactions and applications Hydrogen sulphide : FeS(s) + H2SO4(aq)  FeSO4(aq) + H2S(g) Oxides: S(s) + O2(g)  SO2(g) SO2(g) + H2O(l)  H+(aq) + HSO3-(aq) 2 SO2(g) + O2(g)  2 SO3(g) SO3(g) + H2O(l)  H2SO4(aq) Sulfuric acid: Mg(s) + H2SO4(aq)  MgSO4(aq) + H2(g) C(s) + 2 H2SO4 CO2(g) + 2 SO2(g) + 2 H2O(l) Carbon disulphide : C(s) + 2 S(l)  CS2(l) Applications: H2SO4 (chemical processes; most utilized chemical product at world scale); CS2 (solvent for rubber).

  17. Halogens The halogens are non metals extremely reactive. They form an high number of compounds. In the elementary form they are X2 molecules. The oxidation states can vary from –1 to +7, except fluorine. Occurrence: Cl, Br e I (halides in seawater); CaF2 (fluorite); Na3AlF6 (criolite) Obtaining: Cl2: electrolysis of melted NaCl or an concentrated aqueous solution (chlorine - alkaline process) F2: electrolysis of HF(l) Br2 and I2: oxidation of the ions by Cl2 (displacement reaction)

  18. Reactions Hydrogen halides: H2(g) + X2(g)  2 HX(g) CaF2(s) + H2SO4(aq)  2 HF(g) + CaSO4(s) 2 NaCl(s) + H2SO4(aq)  2 HCl(g) + Na2SO4(aq) Oxides and oxoacids: great variety of compounds. HClO (hypochlorous acid), HClO2 (chlorous acid), HClO3 (chloric acid), HClO4 (perchloric acid) Inter-halogens compounds: XX’; XX’3; XX’5, XX’7 Cl2(g) + F2(g)  2 ClF Cl2(g) + 3 F2(g)  2 ClF3 KI(s) + 4 F2(g)  KF(s) + IF7(g)

  19. Applications Fluorine: NaF (prevention of dental caries); UF6 (separation of uranium isotopes); production of Teflon (-CF2-CF2-) utilized in isolators, plastics, culinary utensils... Chlorine: pulp and paper industry and textiles; NaClO (detergents); Cl2 (swimming pool disinfection); CCl4 and CHCl3 (organic solvents). Bromine: AgBr (photographic films); insecticides... Iodine: anti-septic (tincture of iodine); AgI (artificial formation of clouds)...

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