1A Survey of the Representative Elements 2 The Group 1A Elements 3 The Chemistry of Hydrogen 4The Group 2A Elements 5The Group 3A Elements 6 The Group 4A Elements The representative Elements: Groups 1A – 4A

The representative Elements: Groups 5A – 8A 7The Group 5A Elements 8 The Chemistry of Nitrogen 9The Chemistry of Phosphorus 10The Group 6A Elements 11The Chemistry of Oxygen 12The Chemistry of Sulfur 13The Group 7A Elements 14The Group 8A Elements

Reviewing the Periodic Table Regions Representative elements:  Groups 1A – 8A (Groups 1, 2 & 13-18)  The s and p blocks (orbital s and p are filled) Transition elements:  Groups 3B – 2B (Groups 3 – 12)  The d block (orbitals d are filled)

Reviewing the Periodic Table Regions Lanthanides and Actinides:  Listed separately at bottom of the table  The f block (orbitals 4f and 5f are filled) Metalloids:  Separate metals from nonmetals  B, Si, Ge, As, Sb, Te, Po, & At

Trends of Nuclear Charge and Atomic Sizes Effective nuclear charge increases left-to-right and decreases top-to-bottom; Atomic size decreases left-to-right and increases top-to-bottom;

Atomic Radii of Some Representative Elements (in Picometers)

Trends in Ionization Energy and Electronegativity Ionization energy and electronegativity increase left-to-right and decrease top-to- bottom. 1.Li > Na > K > Rb > Cs; 2.F > Cl > Br > I; 3.C < N < O < F;

Chemical Reactivity Reactivity of metals decreases left-to-right and increases top-to-bottom. Na > Mg > Al; Li < Na < K; Reactivity of nonmetals increases left-to-right and decreases top-to-bottom. N < O < F; F > Cl > Br;

Concept Check Which atom is larger, Na or Cl? Why? Na Cl

Concept Check Which is the larger atom, Li or Cs? Why? Li Cs

Concept Check Which is more reactive and why? (a)Li or Cs? (b)Na or Al? (c)F or I? (d)P or Cl?

Distribution of 18 Most Abundant Elements

Abundance of Elements in the Human Body

Alkali Metals: Sources and Methods of Preparation

Production of Alkali Metals Li and Na are produced by electrolysis of molten chlorides (LiCl and NaCl). K is produced by displace method using molten KCl and Na vapor: KCl (l) + Na (g)  K (g) + NaCl (l)

Group 1A Oxides Reactions of alkali metals with oxygen: 4Li (s) + O 2 (g)  2Li 2 O (g) (simple oxide) 2Na (s) + O 2 (g)  Na 2 O 2 (s) (peroxide) K (s) + O 2 (g)  KO 2 (s) (superoxide)

Important Reactions of Alkali Metals 4Li (s) + O 2 (g)  2Li 2 O (s) 2Na (s) + O 2 (g)  Na 2 O 2 (s) K (s) + O 2 (g)  KO 2 (s) 6M (s) + N 2 (g)  2M 3 N (s) 2M (s) + H 2 O (l)  MOH (aq) + H 2 (g) 2M (s) + X 2 (g)  2MX (s) (M = Li, Na, K, Rb, Cs; X = F, Cl, Br, I)

Exercise #1 Complete and balance each of the following equations: 1.Na (s) + H 2 O (l)  ? 2.Li (s) + N 2 (g)  ? 3.KO 2 (s) + CO 2 (g)  ?

Exercise #2 Predict the products formed by the following reactants: Na 2 O 2 (s) + H 2 O (l) → NaOH (aq) + H 2 O 2 (l)

Uses of Lithium and Lithium Compounds Lithium mainly used to make lithium batteries; LiCl is used in air-conditioning units as dehumidifier; Li 2 CO 3 is used in porcelain enamels, manufacture of tough (pyrex) glasses, and as medication for manic depression;

Important Compounds of Sodium NaCl: 1.As an ingredient in food – Na + is essential to the body for electrolyte balance; 2.Production of sodium metal by electrolysis of molten NaCl; 2 NaCl (l)  2Na (s) + Cl 2 (g) 3.Production of NaOH by electrolysis of aqueous NaCl; 2NaCl (l)  2NaOH (aq) + H 2 (g) + Cl 2 (g)

Important Compounds of Sodium NaHCO 3 - used for making cookies, cakes, and in fire- extinguishers Na 2 CO 3 – used in manufacture of ground glasses and as industrial bases; NaOH – used in manufacture of bleach, as a strong base, and as drain cleaners; The manufacture of household bleach: Cl 2 (g) + 2NaOH (aq)  NaOCl (aq) + NaCl (aq) + H 2 O (l)

Important Compounds of Potassium K + is essential for nervous system; K 2 O is important component in fertilizers; KO 2 is used in confined places like submarines for removal of CO 2 and production of O 2 : 4 KO 2 (s) + 2CO 2 (g)  2K 2 CO 3 (s) + 3O 2 (g)

Hydrogen Most abundant element in the universe, but makes up <1% (by mass) on Earth crust. Isotopes of hydrogen: 1.Hydrogen ( 1 H) - has no neutron; most abundant 2.Deuterium ( 2 H) - has one neutron 3.Tritium ( 3 H) – has 2 neutrons; radioactive (half- life ~ 12.3 yrs)

Isotope Effects Deuterium exhibits significant isotope effects on chemical and physical properties. 1.Freezing points: H 2 O (0.00 o C); D 2 O (3.81 o C) 2.Boiling points: H 2 O (100.0 o C); D 2 O ( o C) 3.Density at 25 o C (g/mL): H 2 O (0.997); D 2 O (1.104)

Hydrides Binary compounds containing hydrogen:  Ionic hydrides: (hydrogen + reactive metals) Examples: LiH, CaH 2  Covalent hydrides: (hydrogen + other nonmetals) Examples: H 2 O, CH 4, NH 3 )  Metallic (interstitial) hydrides: H 2 gas in certain transition metal crystals

Production of Hydrogen Laboratory preparation of hydrogen gas: Mg (s) + 2HCl (aq)  MgCl 2 (aq) + H 2 (g) Zn (s) + H 2 SO 4 (aq)  ZnSO 4 (aq) + H 2 (g) Industrial production method by steam- reformation of hydrocarbon: CH 4 (g) + H 2 O (g)  CO (g) + 3H 2 (g) ;  H = 205 kJ CO (g) + H 2 O (g)  CO 2 (g) + H 2 (g) ;  H = -41 kJ

Uses of Hydrogen 1.Production of Ammonia using the Haber process: N 2 (g) + 3H 2 (g)  2NH 3 (g) 2.Production of Methanol: CO (g) + 2H 2 (g)  CH 3 OH (l) 3.Hydrogenation of vegetable oil: Vegetable oil + H 2 (g)  “Crisco” and Margarine 4.Manufacture of hydrochloric acid H 2 (g) + Cl 2 (g)  2HCl (g)  HCl (aq)

Exercise #3 Predict the products formed by the following reactants: LiH (s) + H 2 O (l) → H 2 (g) + LiOH (aq)

Alkaline Earth Metals Be, Mg, Ca, Sr, Ba, and Ra (radioactive); Very reactive elements; Valence-shell electron configuration: ns 2 Cations = M 2+, has noble gas configuration; Practical importance:  Ca 2+ and Mg 2+ are essential to life;  Mg is a component in light alloys

Occurrence and Preparation Abundance in Earth’s crust: 1.Calcium and magnesium rank 5 th and 6 th, respectively. 2.Magnesium found in the ocean (~0.055 M) and in MgCO 3 (dolomite) 3.Seawater important source of Mg; 4.Calcium found in limestone and sea shells (CaCO 3 ) – most abundant mineral on Earth 5.Mg and Ca are prepared by electrolysis of the molten MgCl 2 and CaCl 2, respectively.

Extraction of Mg from Seawater 1.Mg 2+ (aq) + CaO (s) + H 2 O (l)  Mg(OH) 2 (s) + Ca 2+ (aq) 2.Mg(OH) 2 (s) + 2HCl (aq)  MgCl 2 (aq) + 2H 2 O (l) 3.MgCl 2 (aq)  MgCl 2 (s)  MgCl 2 (l) 4.MgCl 2 (l) electrolysis  Mg (s) + Cl 2 (g) ;

Extraction of Calcium from CaCO 3 CaCO 3 (s) + 2HCl (aq)  CaCl 2 (aq) + H 2 O (l) + CO 2 (g) ; CaCl 2 (aq)  CaCl 2 (s)  CaCl 2 (l) ; CaCl 2 (l) electrolysis  Ca (s) + Cl 2 (g)

Compounds of Alkaline Earth Metals Except for Be, all oxides and halides of alkaline Earth metals are ionic compounds; Beryllium forms covalent compounds; Except for BeO, all oxides of alkaline Earth metals are basic – forms strong basic solutions; BeO is amphoteric;

Uses of Some Alkaline Earth Metals Beryllium: 1.a component in alloys for making tough springs and non-sparking tools 2.Used as X-ray tube window; 3.A neutron source in nuclear reactor;

Uses of Some Alkaline Earth Metals Magnesium is used: 1.in the manufacture of light-weight alloys for aircraft body and parts; 2.as reducing agent in the extraction of silicon, titanium and beryllium; 3.in Grignard reagents for organic synthesis; 4.An ingredient in fireworks and warning flare; Calcium is also used as reducing agent in the extraction of other metals, such as Sc and W;

Important Compounds of Magnesium Mg 2+ is essential to life; Many enzymes require Mg 2+ ; Mg 2+ is an essential component of chlorophyll; MgO is a component in ceramic and used in refractory furnace lining; Mg(OH) 2 is active component of antacid “Milk of Magnesia” MgSO 4 found in fertilizers and food supplements

Important Compounds of Calcium Like Mg 2+, Ca 2+ is essential to life; In cell physiology, movements of Ca 2+ in and out of cytoplasm function as signal for many cellular processes; Ca 5 (PO 4 ) 3 (OH) - in teeth and bone structures; CaCO 3 – forms protective coverings, as in egg and sea shells; CaCO 3 (limestone) - most abundant mineral; 1.Pure CaCO 3 are used as fillers in paint, toothpaste, paper, plastics, etc.; 2.the source for calcium metal and quicklime: Calcination: CaCO 3 (s)  CaO (s) + CO 2 (g)

Important Compounds of Calcium CaO – also called quicklime, uses: 1.important ingredient of Portland cement; 2.industrial base; 3.extraction of Mg from seawater; 4.in metallurgy – as base in steel production; 5.As scrubber to remove toxic gas SO 2 from industrial “flu-gas”: CaO (s) + SO 2 (g)  CaSO 3 (s)

Ca 2+ & Mg 2+ in Water Ca 2+ and Mg 2+ causes water hardness; Soaps do not form leather due to formation of precipitates with Ca 2+ & Mg 2+ ;

A Schematic Representation of a Typical Cation Exchange Resin Cation-exchange resins – large molecules that have many -SO 3 - sites, with Na + as counter ions; Ca 2+ and Mg 2+ bound more strongly to anionic sites and displace Na+.

Exercise #4 Complete and balance the following equations: 1.Mg (s) + HCl (aq)  ? 2.MgH 2 (s) + H 2 O (l)  ? 3.Ca (s) + H 2 O (aq)  ? 4.CaO (s) + SO 2 (g)  ?

Valence-shell electron configuration: ns 2 np 1 Group 3A elements show increasing metallic character going down the group. Boron: a metalloid, forms covalent network solid, and highest melting point in the group Group 3A

Some Physical Properties, Sources, and Methods of Preparation

Some Important Reactions

Properties of Boron (1s 2 2s 2 2p 1 ) A metalloid; forms covalent network solid; highest melting point in the group, and the least reactive All boron compounds are covalent molecules; Boron molecules, such as BF 3, have incomplete octet and acts as Lewis acid, example: BF 3 + :NH 3  F 3 B:NH 3 Boron hydrides acquire octet by forming H-bridges; Boron oxide, B 2 O 3, forms weak boric acid, B(OH) 3 ;

Aluminum Electron configuration: 1s 2 2s 2 2p 6 3s 2 3p 1 or [Ar] 3s 2 3p 1 Third most abundant element (and most abundant metal) in the Earth’s crust; Most important metal of Group 3A; US annual production: over 5 millions tons;

Aluminum Production Extracted from bauxite, Al 2 O 3  nH 2 O; Produced by the Hall-Heroult process - electrolysis of molten Al 2 O 3 -Na 3 AlF 6 (cryolite) mixture at ~ 960 o C Aluminum production is an energy intensive process Energy consumption: ~ 54 MJ/kg Al (~3% of electrical energy supply) Re-cycling saves up to 95% of this energy; (Re-cycle an aluminum can and power your desk-top monitor up to 3 hours)

Importance of Aluminum Lightweight metal (density = 2.70 g/cm 3 ); Forms strong, lightweight alloys with copper and magnesium for aircraft bodies and parts; High resistance to corrosion - extensively used to make beverage containers (soda drinks cans); Also used as reducing agent in the fuel during space shuttle launching.

Chemical Properties of Aluminum Reactive metal, readily oxidized by atmospheric O 2 to form Al 2 O 3 ; Al 2 O 3 forms protective coating (an anodic protection) that prevents further corrosion of the metal; Al 2 O 3 is amphoteric - reacts with both strong acids & bases; Aluminum reacts with halogens to form AlX 3 ; Al 2 O 3 and AlF 3 are strictly ionic compounds; Other halides are ionic with covalent characteristics.

Reactions of Aluminum With strong acids: 2Al (s) + 6 HCl (aq)  2AlCl 3 (aq) + 3H 2 (g) ; 2Al (s) + 3H 2 SO 4 (aq)  Al 2 (SO 4 ) 3 (aq) + 3H 2 (g) ; 2Al (s) + 2HNO 3 (aq)  Al 2 O 3 (s) + 2NO (g) + H 2 O (l) (The third reaction does not occur completely because the oxide forms protective coating to prevent further reaction.) With a strong base: 2Al (s) + 6H 2 O (l) + 2NaOH (aq)  2NaAl(OH) 4 (aq) + 3H 2 (aq) ;

Important Compounds of Aluminum Al 2 O 3 – source of aluminum metal and forms protective coating to the metal to prevent corrosion; Al 2 (SO 4 ) 3 – most important industrial compound; 1.use in municipal water treatment plants; 2.Prepared by reaction of H 2 SO 4 with Al 2 O 3 or Al(OH) 3 : Al 2 O 3 (s) + 3H 2 SO 4 (aq)  Al 2 (SO 4 ) 3 (s) + 3H 2 O (l) 2Al(OH) 3 (s) + 3H 2 SO 4 (aq)  Al 2 (SO 4 ) 3 (s) + 6H 2 O (l)

Exercise #5 1.Classify the following oxides as acidic, basic or amphoteric. B 2 O 3 Al 2 O 3 In 2 O 3 Balance the following equations: 1.B (s) + HNO 3 (aq)  B 2 O 3 (s) + NO (g) + H 2 O 2.Al (s) + H 2 SO 4 (aq)  Al 2 (SO 4 ) 3 (aq) + H 2 (g) 3.Al 2 O 3 (s) + HCl (aq)  AlCl 3 (aq) + H 2 O (l)

Group 4A (vsec: ns 2 np 2 ) Carbon exists in 3 allotropic forms: graphite, diamond, and the “bucky-ball”. Contains: a nonmetal (C), two metalloids (Si & Ge), and two metals (Sn & Pb); Graphite has sp 2 hybridization; Graphite is soft and conduct electric current; Diamond contains sp 3 hybridization and forms covalent network solids; does not conduct electricity; Diamond is the hardest material on Earth.

Some Physical Properties, Sources, and Methods of Preparation

Contains two most important elements on earth: carbon and silicon. Can form four covalent bonds to nonmetals.  CH 4 and SiF 4 Group 4A

Some Important Reactions

Carbon: 1s 2 2s 2 2p 2 Most important element on Earth – forms the basic skeletal structures of all living things; Carbon forms strong covalent bonds with many elements and with itself; Carbon forms sp, sp 2, and sp 3 hybridizations; In sp hybridization, each carbon forms 2  - and 2  - bonds; example in H ― C ≡ C ― H In sp 2, each carbon forms 3  - and a  - bonds; In sp 3 hybridization each carbon forms 4  -bonds;

Important Compounds of Carbon CO – toxic gas (binds to hemoglobin); forms during combustion of carbon in limited oxygen supply; used in methanol production. CO 2 – end-product of combustion of carbon or carbon-containing compounds; greenhouse gas that keeps Earth temperature relatively warm; CO 2 is essential to life – used by plants in photosynthesis; NaHCO 3 – used as baking soda for cooking and as in fire-extinguishers; Na 2 CO 3 – used in glass manufacture; CaCO 3 – used in steel production;

Exercise #6 Draw Lewis structures for the following ions and molecule and propose hybridization on the carbon atom in each ion or molecule. 1.CO 2 2.CO HCO H 2 CO 3 5.CF 4

Other Important Compounds of Carbon CH 4 – major component of natural gas; used as fuel and for the production of hydrogen gas; C 3 H 8 and C 4 H 10 – used as fuel; C 6 H 14, C 7 H 16, C 8 H 18, and C 9 H 20 are components in gasoline, with C 8 H 18 as the major component; C 6 H 12, (cyclohexane), C 6 H 14 (hexane), and C 6 H 6 (benzene) are important organic solvents; C 2 H 4, C 2 H 3 Cl, C 2 F 4, and H 2 NCH 2 CH 2 CH 2 CH 2 CH 2 CH 2 NH 2 (among others) are important monomers for polymers, such as polyethylene, PVC, Teflon, nylon, and polyester.

Chemistry of Silicon Silicon - a metalloid; a covalent network solid with diamond-like structure; very important in the electronic industries - forms semi-conductors. Silicon dioxide or silica (SiO 2 ) - the second most abundant substance on the Earth’s crust; also the source of silicon; SiO 2 - used in the manufacture of glass and ceramics; Silicon carbide (SiC) has diamond-like structure; used to make abrasive and heat resistant ceramics.

Production of Silicon SiO 2 (s) + 2C (s)  Si (s) + 2CO (g) ; Si (s) + 2Cl 2 (g)  SiCl 4 (g) ; SiCl 4 (g) + 2Mg (s)  Si (s) + 2MgCl 2 (s) ; Final purification done by “zone-refining”

Tin and Lead Both are soft metals; T m ( o C): Sn (232) & Pb (327) Tin - used mainly in tin-plating for making food cans, for making solders, bronze, and pewters; Lead - mainly used to make automobile batteries; some are used as lead shots and radiation shields; Both metals form +2 and +4 oxidation states; Reacts with O 2  SnO, SnO 2, PbO & PbO 2 ; Reacts with Cl 2  SnCl 2, SnCl 4, PbCl 2 & PbCl 4 ; SnO, PbO, SnCl 2, and PbCl 2 are ionic; SnO 2, PbO 2, SnCl 4, and PbCl 4 are molecular;

Important Compounds of Tin and Lead SnCl 2 – used as reducing agent, tin plating, catalyst; SnF 2 – additive in toothpaste to prevent cavity; PbO – used in ceramic glaze, and cement; PbO 2 – oxidizing agent and battery electrodes; PbCrO 4 – for making yellow pigment for paint;

Valence-shell configuration: ns 2 np 3 Exhibits varied chemical properties. 1.N and P are nonmetals; 2.As and Sb are metalloids; 3.Bi is a metal (the heaviest non-radioactive element) Group 5A

Some Physical Properties, Sources, and Methods of Preparation

Oxides of Group 5A Elements Nitrogen: N 2 O, NO, N 2 O 3, NO 2, N 2 O 4, N 2 O 5 ; Phosphorus: P 4 O 6 & P 4 O 10 ; Arsenic: As 2 O 3 (As 4 O 6 ) & As 2 O 5 ; Antimony: Sb 2 O 3 & Sb 2 O 5 Bismuth: Bi 2 O 3 & Bi 2 O 5

Chlorides of Group 5A Elements Nitrogen: only NCl 3 ; Phosphorus: PCl 3 and PCl 5 ; Arsenic: AsCl 3 and AsCl 5 ; Antimony: SbCl 3 and SbCl 5 ; Bismuth: BiCl 3 All are molecular compounds.

Reactions of Oxides and Chlorides 3NO 2 (g) + H 2 O (l)  2HNO 3 (aq) + NO (g) ; N 2 O 5 (g) + H 2 O (l)  2HNO 3 (aq) P 4 O 10 (s) + 6H 2 O (l)  4H 3 PO 4 (aq) ; As 2 O 5 (s) + 3H 2 O (l)  2H 3 AsO 4 (aq) ; PCl 5 (s) + 4H 2 O (l)  H 3 PO 4 (aq) + 5HCl (aq) ; AsCl 5 (s) + 4H 2 O (l)  H 3 AsO 4 (aq) + 5HCl (aq) ; 2SbCl 5 (s) + 5H 2 O (l)  Sb 2 O 5 (s) + 10HCl (aq) ;

The Chemistry of Nitrogen The triple bonds (N  N) in N 2 provide high stability to the molecule; Many reactions involving nitrogen gas are endothermic and compounds containing nitrogen decompose exothermically to the elements. N 2 (g) + O 2 (g )  2NO (g)  H  = 180 kJ 2NO 2 (g)  N 2 (g) + O 2 (g) ;  H  = -68 kJ N 2 H 4 (g)  N 2 (g) + 2H 2 (g) ;  H  = -95 kJ

Nitrogen Fixation The process of transforming N 2 to other nitrogen–containing compounds. Atmospheric fixation (occurs naturally during thunderstorm): N 2 (g) + O 2 (g)  2NO (g) ;  H o = 180 kJ 2NO (g) + O 2 (g)  2NO 2 (g) ;  H o = -112 kJ 3NO 2 (g) + H 2 O (l)  2HNO 3 (aq) + NO (g) ;  H o = -140 kJ

Biological Nitrogen Fixation Fixation of atmospheric N 2 by bacteria living in soils and water; some live in root nodules; Plants such as legumes and alfafa have root nodules that contain nitrogen-fixing bacteria – they benefit directly from these bacteria; Other plants benefit when the bacteria die and release absorbable forms of nitrogen (NH 3, NH 4 +, and NO 3 - ) to the soils;

Biological Nitrogen Fixation In nitrogen-fixing bacteria 1.Atmospheric N 2 is first reduced to NH 3 ; 2.In bacterial cells, NH 3 becomes NH 4 +, oxidized to NO 2 - and then to NO 3 - ; 3.NH 3, NH 4 +, and NO 3 - can be released into the surroundings (water or soils) and become available to plants; Denitrifying bacteria (in soils) change NO 3 - back to NO 2 -, NH 3, and finally to N 2 to complete the biological nitrogen cycle.

Biological Fixation and The Nitrogen Cycle

Industrial Nitrogen Fixation Industrial Fixation (the Haber Process): N 2 (g) + 3H 2 (g)  2NH 3 (g)  H  = -92 kJ Most NH 3 are converted to: 1.Fertilizers (~70%) 2.Nitric acid, HNO 3 (~20%) 3.Hydrazine, N 2 H 4, and monomers for various plastics and nylons.

The Haber Process

Important Hydrides of Nitrogen Ammonia, NH 3 (most important hydride)  Production of fertilizers (NH 4 NO 3, (NH 4 ) 2 SO 4, (NH 4 ) 3 PO 4, and CO(NH 2 ) 2 ), HNO 3, and N 2 H 4 Hydrazine, N 2 H 4  Rocket propellant, manufacture of plastics, agricultural pesticides; Monomethylhydrazine, CH 3 N 2 H 3  Rocket fuels

Oxides of Nitrogen In its oxides nitrogen has oxidation states ranging from +1 to N 2 O (+1) 2.NO (+2) 3.N 2 O 3 & HNO 2 (+3) 4.NO 2 (+4) 5.N 2 O 5 & HNO 3 (+5)  In other compounds, nitrogen could have oxidation states of -1 to -3.  NH 2 OH (-1), N 2 H 4 (-2), and NH 3 (-3)

Nitrogen Oxyacids Nitric acid, HNO 3 Nitrous acid, HNO 2

Production of HNO 3 -The Ostwald Process

Production of Nitric Acid Oswald Process: 1.NH 3 (g) + O 2 (g)  NO (g) + H 2 O (g) ; 2.2NO (g) + O 2 (g)  NO 2 (g) ; 3.3NO 2 (g) + H 2 O (l)  2HNO 3 (aq) + NO (g) ;

Reactions of Nitric Acid HNO 3 - a strong acid and an oxidizing agent; Reactions with metals does not produce H 2 1.Cu (s) + 4HNO 3 (16 M)  Cu(NO 3 ) 2 (aq) + 2NO 2 (g) + 2H 2 O (l) ; 2.3Cu (s) + 8HNO 3 (aq, 6 M)  3Cu(NO 3 ) 2 (aq) + 2NO (g) + 4H 2 O (l) ; 3.4Zn (s) + 10HNO 3 (aq, 3 M)  4Zn(NO 3 ) 2 (aq) + N 2 O (g) + 2H 2 O (l) ;

Allotropes of Phosphorus White Phosphorus: P 4 (tetrahedral) - very reactive Black Phosphorus: crystalline structure - much less reactive Red Phosphorus: amorphous with P 4 chains

Allotropes of Phosphorus (a) White Phosphorus (b) Black Phosphorus (c) Red Phosphorus

Oxides of Phosphorus Reaction of white phosphorus with oxygen: 1.P 4 (s) + 3O 2 (g)  P 4 O 6 (l) ; (o.s. of P = +3) 2.P 4 (s) + 5O 2 (g)  P 4 O 10 (s) ; (o.s. of P = +5) Reactions of phosphorus oxides with water: 1.P 4 O 6 (l) + 6H 2 O (l)  4H 3 PO 3 (aq) ; 2.P 4 O 10 (s) + 6H 2 O (l)  4H 3 PO 4 (aq) ;

Oxyacids of Phosphorus Phosphoric acid, H 3 PO 4 - triprotic Phosphorous acid, H 3 PO 3 - diprotic Hypophosphorous acid, H 3 PO 2 - monoprotic

Phosphorus Halides Reactions of white phosphorus with halogens: 1.P 4 (s) + 6X 2  4PX 3 (l) ; 2.P 4 (s) + 10X 2  4PX 5 (s) ; Examples of reactions: 1.P 4 (s) + 6Cl 2 (g)  4PCl 3 (l) ; 2.P 4 (s) + 10Cl 2 (g)  4PCl 5 (s) ; 3.PCl 3 (l) + Cl 2 (g) ⇄ PCl 5 (s) ;

Reactions of Phosphorus Halides Reactions with water: PCl 3 (l) + 3H 2 O (l)  H 3 PO 3 (aq) + 3HCl (aq) ; PCl 5 (s) + 4H 2 O (l)  H 3 PO 4 (aq) + 5HCl (aq) ;

Important Compounds of Phosphorus Ca 3 (PO 4 ) 2 & Ca 5 (PO 4 ) 3 F : source of phosphorus Ca 5 (PO 4 ) 3 (OH) : forms bones and teeth P 4 O 10 : formation of H 3 PO 4 H 3 PO 4 : production of fertilizers & phosphates H 2 PO 4 - & HPO 4 2- : phosphate buffers Na 3 PO 4 : scouring powder and paint remover Na 5 P 3 O 10 : fabric softeners ADP & ATP : storage of metabolic energy PCl 5 : precursor for lithium hexafluorophosphate (LiPF 6 ), an electrolyte in lithium ion batteries;

Exercise #7 Draw Lewis structures for the following molecules: 1.N 2 O 2.NO 2 3.HNO 3 4.H 3 PO 4 (triprotic acid – 3 ionizable H + ) 5.H 3 PO 3 (diprotic acid – 2 ionizable H + ) 6.H 4 P 2 O 7 (tetraprotic – 4 ionizable H + ) 7.H 5 P 3 O 10 (pentaprotic – 5 ionizable H + ) 8.PCl 3 and PCl 5

Valence-shell configuration: ns 2 np 4 O, S, Se, Te, Po None of the Group 6A elements behaves as a typical metal. Elements form covalent bonds with other nonmetals. Group 6A

Some Physical Properties, Sources, and Methods of Preparation

Oxygen O 2 makes up 21% of the Earth’s atmosphere. O 3 (ozone) exists naturally in the upper atmosphere (the stratosphere) of the Earth.  Ozone layer absorbs UV light and acts as a screen to block most uv-radiation from reaching the Earth’s surface.  We now know that Freons (CFCs) and are promoting destruction of ozone layer.

Various Forms of Oxides Metal oxides (ionic) 1.Nonconductor – example: MgO 2.Semiconductor – example: NiO 3.Conductor – example: ReO 3 4.Superconductor – example: YBa 2 Cu 3 O 7 Nonmetal oxides (covalent): Molecular oxides – examples: CO 2, NO, NO 2, N 2 O, SO 2, P 4 O 10, etc. Covalent network oxide – SiO 2

Characteristics of Oxides Metallic oxides – basic or amphoteric Examples: Na 2 O (basic); Al 2 O 3 (amphoteric) Semi-metallic oxides – mild to weakly acidic Example: B 2 O 3 Nonmetallic oxides – weak to strong acids Examples: 1.SO 2 (g) + H 2 O (l)  H 2 SO 3 (aq) (weak acid); 2.SO 3 (g) + H 2 O (l)  H 2 SO 4 (aq) (strong acid);

Ozone 3O 2 (g)  2O 3 (g) K  10 57

Sulfur is found in nature both in large deposits of the free element and in ores such as: Galena = PbS, Cinnabar = HgS, Pyrite = FeS 2, Gypsum = CaSO 4  2H 2 O), Epsomite = MgSO 4.7H 2 O, and Glauberite = Na 2 Ca(SO 4 ) 2 Sulfur

Sulfur Mining: Frasch Process

Aggregates of Sulfur

Sulfur Oxides and Oxyacids S (s) + O 2 (g)  SO 2 (g) 2SO 2 (g) + O 2 (g)  2SO 3 (g) SO 2 (g) + H 2 O (l)  H 2 SO 3 (aq) SO 3 (g) + H 2 O (l)  H 2 SO 4 (aq) H 2 SO 3 – diprotic; weak acid H 2 SO 4 – diprotic; strong acid

Sulfuric Acid Productions: 1.S 8 (s) + 8 O 2 (g)  8SO 2 (g) ; 2.2H 2 S (g) + 3 O 2 (g)  2SO 2 (g) + 2H 2 O (l) ; 3.FeS 2 (s) + 11 O 2 (g)  Fe 2 O 3 (s) + 8SO 2 (g) ; 1.2SO 2 (g) + O 2 (g)  2SO 3 (g) ; (V 2 O 5 /K 2 O catalyst) 2.2SO 3 (g) + H 2 SO 4 (l)  H 2 S 2 O 7 (l) ; 3.H 2 S 2 O 7 (l) + H 2 O (l)  2H 2 SO 4 (l) ;

Important Compounds of Sulfur H 2 SO 4 – most important compound, for manufacture of fertilizer, soap, detergents, metal and textile processing, sugar refinery, and organic syntheses; SF 4 – for fluoridation SF 6 – as insulating and inert blanket Na 2 S 2 O 3 – as reducing agent and complexing agent for Ag + in photography (called “hypo”); P 4 S 3 – in “strike-anywhere” match heads

Exercise #8 Draw Lewis structures for the following molecules: 1.SO 2 2.SF 2 3.SF 4 4.SF 6 5.H 2 SO 4 6.H 2 SO 3 7.H 2 S 2 O 7

The Halogens All nonmetals: F, Cl, Br, I, At Most reactive nonmetal group; Not found as free elements in nature. Mainly found as halide ions (X – ) in various minerals and in seawater.

Trends in Selected Physical Properties

Some Physical Properties, Sources, and Methods of Preparation

Preparation of Hydrogen Halides H 2 (g) + X 2 (g)  2HX (g) When dissolved in water, the hydrogen halides behave as acids, and all except hydrogen fluoride are completely dissociated.

Halogen Oxyacids and Oxyanions All halogens except fluorine combine with various numbers of oxygen atoms to form oxyacids. Strengths of oxyacids vary directly to the number of oxygen atoms bonded to the halogen - acid strength increases as more oxygens are added.

The Known Oxyacids of the Halogens

Interhalogen Compounds Formation: Cl 2 (g) + 3F 2 (g)  2ClF 3 (g) ; Br 2 (l) + 3F 2 (g)  2BrF 3 (l) ; Br 2 (l) + 5F 2 (g)  2BrF 5 (l) ; I 2 (s) + 3Cl 2 (g)  I 2 Cl 6 (s) ; (dimeric form)

Reactions of Interhalogen Compounds ClF 3 & BrF 3 – fluoridating agents 1.2B 2 O 3 (s) + 2BrF 3 (l)  4BF 3 (g) + Br 2 (l) + 3 O 2 (g) 2.P 4 (s) + 5ClF 3 (g)  4PF 3 (g) + Cl 2 (g) + 3ClF (g) Reaction with water is explosive: 1.ClF 3 (g) + 2H 2 O (l)  HClO 2 (aq) + 3HF (aq) ; 2.BrF 5 (l) + 3H 2 O (l)  HBrO 3 (aq) + 5HF (aq) ;

Chemistry of Chlorine Most important halogen Laboratory preparation from MnO 2, NaCl and H 2 SO 4 : 2NaCl (s) + MnO 2 (s) + 2H 2 SO 4 (l)  Cl 2 (g) + MnSO 4 (s) + Na 2 SO 4 (s) + 2H 2 O (l) Industrial production: Chlorine is a by-product in the electrolysis of NaCl, MgCl 2, CaCl 2, ScCl 3, etc.

Major Uses of Chlorine Production of chlorinated organic compounds; Production of hydrochloric acid; Production of bleach solution and bleach powder; Treatment of municipal water.

Production of Bleach Solution 1.Cl 2 (g) + 2NaOH (aq)  NaOCl (aq) + NaCl (aq) + H 2 O (l)

Production of Bleach Powder 2Cl 2 (g) + 2Ca(OH) (aq)  Ca(OCl) 2 (s) + CaCl 2 (aq) + 2H 2 O (l)

Production of Other Oxidizing Agents 3Cl 2 (g) + 6NaOH (aq)  NaClO 3 (aq) + 3NaCl (aq) + 3H 2 O (l) 2NaClO 3 (s) + SO 2 (g) + H 2 SO 4 (aq)  2ClO 2 (g) + 2NaHSO 4 (aq)

Oxides and Oxyacids of Chlorine Oxides of chlorine and its oxidation number (in parenthesis): Cl 2 O (+1), Cl 2 O 3 (+3), ClO 2 (+4; unstable), Cl 2 O 5 (+5), Cl 2 O 7 (+7; highest possible) Chlorine oxyacids in increasing acid strength HOCl < HClO 2 < HClO 3 < HClO 4 ; HClO 4 is a strong oxidization agent

Important Compounds of Chlorine NaCl – for electrolyte balance NaOCl – household bleach solution Ca(OCl) 2 – bleach for water & sewage treatment ClO 2 – bleach for paper production NaClO 3 – production of industrial bleach (ClO 2 ) KClO 3 – oxidizer in fireworks and matches NaClO 4 – production of HClO 4 and NH 4 ClO 4 NH 4 ClO 4 – oxidizer in booster rocket fuel

Exercise #9 Draw Lewis structures for the following molecules: 1.ClF 3 2.BrF 5 3.HOCl 4.HOClO 5.HOClO 2 6.HOClO 3

Noble Gases He and Ne form no compounds. Kr and Xe have been observed to form compounds with oxygen and fluorine: Xe (g) + 2F 2 (g)  XeF 4 (s) Xe (g) + 3F 2 (g)  XeF 6 (s) XeF 6 (s) + 3H 2 O (l)  XeO 3 (aq) + 6HF (aq) XeF 6 (s) + 2H 2 O (l)  XeO 2 F 2 (aq) + 4HF (aq) XeF 6 (s) + H 2 O (l)  XeOF 4 (aq) + 2HF (aq)

Selected Properties

Concept Check Which of the following groups is the most reactive? a) Group 1A Elements b) Group 5A Elements c) Group 6A Elements d) Group 8A Elements

Concept Check Which of the following groups does not contain at least one element that forms compounds with oxygen? a) Group 4A Elements b) Group 5A Elements c) Group 6A Elements d) Group 7A Elements e) All of these groups contain at least one element that forms compounds with oxygen.

Exercise #10a Draw Lewis structures for the following molecules, propose hybridization, and predict whether each molecule is polar or nonpolar. 1.BF 3 2.NF 3 3.ClF 3 4.SiF 4 5.SF 4 6.XeF 4

Exercise #10b Draw Lewis structures for the following molecules. 1.BeCl 2 2.GeF 2 3.XeF 2 4.XeOF 2 5.XeO 2 F 2 6.XeOF 4