DIC

Chlorine oxides

There are six known chlorine oxides, we will only describe ClO and ClO2 Both are odd electron species = free radicals

band theory

derived from molecular orbital theory metallic bonding can be used to see why subtances are electrical conductors or nor or semiconductors. in metals bands overlap and allow a free movement of electrons in non metals bands are widely separated so no electron movement can occur luster for metals

unpaired electrons:NMR

each spin state (+1/2 or -1/2) has the same energy. However, in a magnetic fi eld, the spin can be either parallel with the fi eld or opposed to it, and the parallel arrangement has lower energy. The splitting of (difference between) the two energy levels is very small and corresponds to the radio frequency range of the electromagnetic spectrum

isoelectronic series

share the same total number of valence electrons and the same total sum of electrons.

Bigeleisen-Mayer formulation

showed that bonds to light isotopes are easier to break than those to heavier isotopes. Thus, the heavy isotope of an element will favor chemical species in which it is bound more strongly.

Reactions that occur in HF

Acid/base reaction HF(aq) + H2O(l) → H3O+(aq) + F-(aq) At high concentrations, HF2- is formedF-(aq) + HF(aq) → HF2-

Reactions that occur in HF

Acid/base reactionHF(aq) + H2O(l) → H3O+(aq) + F-(aq) At high concentrations, HF2- is formedF-(aq) + HF(aq) → HF2- Attack on glass forms hexafluorosilicate:SiO2(s) + HF(aq) → SiF62-(aq) + 2 +H+(aq) + 2H2O(l)Can be used for etching glass. Use to make ofther fluoride compounds Sodium fluoride for water fluoridationNaOH(aq) + HF(aq) → NaF(aq) + + 2H2O(l) KOH gives the saslt potassium hydrogen fluoride that is used in the cell to make fluorine gasKOH(aq) + 2HF(aq) → HF2-(aq) + 2H2O(l) Indutrial synthesis from calcium fluoride and sulfuric acid:CaF2(s) + H2SO4(aq) → HF(g) + CaSO4(aq)

Halide ions are detected by precipitation with Ag+

AgCl - white AgBr - cream AgI - yellow (Confirmation add ammonia, Chloride and bromide form complexes:AgCl(s) + 2NH3 → [Ag(NH3)2]+ Chloride and bromide also a light sensitive, turning gray of a perio of a few minutes.

Sodium Carbonate

Alkali metals and ammonium are the only soluble caronates. sodium compound may be:anhydrous Na2CO3(s) (soda ash),monohydrate Na2CO3(s)·H2O,or most commonly asthe decahydrate, Na2CO3(s)·10H2O (washing soda) The decahydrate easily loses water of crystallization, this prcocess is called efforescing.Na2CO3(s)·10H2O(s) → Na2CO3(s)·H2O(s) + H2O(l) Sodium carbonate is obtained from the mineral trona. Trona is a primarily a compound called sodium sequicarbonate:Na2CO3·NaHCO3·2H2OThis is a compound not a mixture of sodium carbonate and bicarbonate.It ia a compound better written as Na3CO3·HCO3·2H2O(Sequi = 1.5 the ratio of (bi)carbonate to sodium ion) Heating trona yields the carbonate : 2[Na2CO3·NaHCO3·2H2O(s)] → 3Na2CO3(s) + 5H2O(g) + CO2(g) Sodium carbonate may be produced by the Solvay or soda ammonium process:2NaCL(s) + CaCO3 ⇔ Na2CO3(S) + CaCl2(s)the equilibrium is shifted to the right by using aqueous ammonia

Features of Alkali Compounds

Alkali metals form only +1 cationa, mostly compounds are ionic. Physical Proerties mp and density Can stabiliza large anion such as HCO3- due to low charge density Are hydrated in water, but hydration enthalpy is small. Very few hydrated salts (LiOH·8H2O is one) All ionic compunds give disticntive flame colors Flame colors are explained by excited valence electron falling back to the ground state:

Iodide

Iodide is a reducing agent so it often prevents formation of higher oxidation state iodides.The most stable iodide is usually the lowest stable oxidation state of the metal.This Cu(II) iodide is not stable. If it were to form the iodide ion would reduce it to Copper(I).2Cu2+(aq) + 4I-(aq) → 2CuI+(aq) + I2(s)

Uses of the Noble Gases - Neon, Argon,

Argon is used for inert atmosphere experiments. Neon lights. Tube with neon. High voltage discharge. Emission spectra is shown. Other gases may be used as well. Low conductivity of heat allows use as filling for insulating windows. Argon in air comes from electron capture by potassium-4040K + e- → 40Ar (a photon is converted to a neutron, reducing Z value by one.)

Reasons for and against placing hydrogen in Group 1 - Alkali metal group

Argument for placement Forms monopositive H+ (H3O+) Has a single s electron Argument against placement Is not a metal ion Does not react with water

Reasons for and against placing hydrogen in Group 17 - Halogen group

Argument for placement Is a nonmetal Forms a diatomic molecule Argument against placement Rarely forms mononegative ion, H 2 is comparatively nonreactive

Group Trends

Astatine may be rarest element on earth. Only 44 mg in entire earth's crust!! Melting and boiling points of elemental forms All have odd atomic numbers, so few isotopes. 19F only one 127I only one 35Cl (76%) and 37Cl (24%) 79Br (51%) and 81Br (49%)

Uses of HF

Attack on glass forms hexafluorosilicate:SiO2(s) + 6HF(aq) → SiF62-(aq) + 2H+(aq) + 2H2O(l)Can be used for etching glass. Use to make other fluoride compounds Sodium fluoride for water fluoridationNaOH(aq) + HF(aq) → NaF(aq) + H2O(l) KOH gives the salt potassium hydrogen fluoride that is used in the cell to make fluorine gasKOH(aq) + 2HF(aq) → KHF2 (aq) + H2O(l)

Chlorine monoxide

ClO Important only in upper atmospheric chemistry. chloro-flurocarbons dissociates into free chlorine atoms A series of reactions occur 1) The chlorine atoms react with ozone (Doubled to supply 2 ClO molecules:2Cl(g) + 2O3(g) → 2ClO(g) + 2O2(g) 2) The odd electron chlorine monoxide dimerizes by collisions with other small molecules, M2ClO(g) + M → Cl2O2(g) + M*(M* is an excited state which will decay back to the ground state) 3) Sunlight decomposes the dimer removing Cl atoms:Cl2O2(g) → ClO2(g) + Cl(g) 4) Sunlight removes the other Cl atom:ClO2(g) → O2(g) + Cl(g)Summing these 4 reactions: 2O3(g) → 3O2(g)Net result: destruction of the ozone layer catalyzed by free Cl atoms.

Uses of hydrochloric acid

107 tonnes a year worldwide removing rust from steel Fe2O3(s) + 6HCl (aq) → FeCl3 (aq) + 3H2O(liq) purification of glucose and corn syrup Oil and gas well treatment Chlorine containing chemical synthesis

Biological Aspects for halogens

All Stable halogens have biological functions. Not true of any other group. Some plants produce fluoroacetate ion, FC2-COO-. The electron withdrawing of the fluoro make the acid a strong acid. fluoroacetate is about the same size as acetate, and it blocks the Krebs cycle. Sodium salt of the acid is used to poison coyotes Chloride ion balances the charges in our bodies. Organic chlorine is usually poisonous. DDT, PCB, etc. Of special concern is trihalomethanes such as Cl3CH, generated from decomposition of organic matter when water systems are chlorinated. An alternative it chlorination is use of ozone or chlorine dioxide which do not form the trihalomethanes. Some marine organisms synthesize organobromine compounds of unknown function. Methyl bromide is used as a fumigant for pests from microbes to insects to weeds. It is volatile so little residue is left, but it is an ozone destroyer. It is poisonous to humans and livestock (Central nervous system and respiratory poison) 75% of iodine in humans is found in the thyroid gland in one hormone thyroxine. The hormone functions to regulate neuromuscular function, and reproductive functioning. Deficiency causes goiter. To prevent this condition, salt is iodized. Why iodine? It seems to be size and fit of enzyme active site. Substitution of isopropyl for iodine maintains hormonal activity

hydrides

Binary compounds of hydrogen are hydrides. Hydrogen is in the middle of the electronegativity scale Ionic compounds with metals of the left side of the table Metallic compounds with transition metals Covalent compounds with elements on the right. Polarity increases toward right. onic hydrides Hydrogen has a strong bond and small electron affinity, so formation of Hydride ion has an overall positive enthalpy. 1/2H2 → H(g) ΔH = +218 kJH(g) + e- → H-(g) ΔH = -69 kJSum is +149 kJ Compare Cl- ion formation which has ΔH = -248 kJOnly cations with low ionization energy will allow entropy be favored to give an ionic hydride. onic hydrides react explosively with water:CaH2(s) + 2H2O(l) → Ca(OH)2(s) + 2H Covalent hydrides are divided into three categories (Class 1) Hydrogen is neutral H2Se or PH3 (Class 2) Hydrogen is positive CH4 (and all hydrocarbons) H2O NH3 HFCertain compounds of this class may form hydrogen bondsthis has a great effect on boiling points

uses of chlorine dioxide

Bleaching flour bleaching wood pulp water treatment (does not chlorinate hydrocarbons like Cl2) Disinfectant, was used to kill Anthrax in offices in 2001 Synthesis is a redox reaction:2ClO3-(aq) + 4H+(aq) + 2Cl- → 2ClO2(g) + Cl2(g) + 2H2O(l) Sulfur dioxide gets rid of the chlorine by reducing it to chloride ion:Cl2(g) + SO2 + 2H2O(l) → H2SO4(aq) + 2HCl(aq)

Other Noble Gas Compounds

C6F5Xe+ ion, an organic xenon compound with a Xe-C bond. For Kr, [H-C≡N-Kr-F]+ can be stabilized with AsF6- tetraxenogold(II) ion

Cyanide as a pseudo halogen

CN- acts chemically like a halide. Note N≡C-C≡N, the pseudo dihalogen, exists. Chemical similarities AgCN is insoluble AgCN forms a soluble complex with ammonia AgCN(s) + 2NH3 → [Ag(NH3)2]+ + CN-HCN is a weak acid like HF CN- forms transition metal complexes similar to halides: Compare [Cu(CN)4]2- and [CuCl4]2- (both tetrahedral) or [Ni(CN)4]2- and [NiCl4]2- (both square planar) CN- is reduced to the pseudo-dihalogen, cyanogen. 2Cu2+(aq) + 4CN-(aq) → 2CuCN(aq) + (CN)2(g) Reaction with hydroxide gives cyanate and cyanide analogous to formation of HClO/Cl- (CN)2(aq) + 2OH-(g) → CN-(aq) + CNO-(aq) + H2O Inter-halogen compounds exist: I-C≡N

There are individual test for each halide.

Chloride - addition of K2Cr2O7/ H2SO4 forms deep red chromyl chloride liquid, CrO2Cl2 If the vapors are bubbled through water, yellow chromic acid forms, H2CrO4 Bromide and iodide - chlorine water oxidizes the bromide or iodide to the elements, giving the water a yellow to brown color. Cl2(aq) + 2Br2(aq) → 2Cl-(aq) + Br2(aq) Adding a non-polar solvent, like carbon tetrachloride, extracts the dihalogen: Br2 = red, and I2 = purple

Halides

Chlorides are classified as ionic (with metals) or Covalent (with non-metals).The chemical behavior of these two types is quite different.

Chlorine

Chlorine gas is poisonous and was used in chemical warfare in WWI On the other hand, small doses in water effectively kill microorganisms Smal scale lab Preparation by permanganate oxidation of HCl:anode (oxidation) HCl(aq) → 2H+(aq) + Cl2(g)+ 2e- cathode (redictin) MnO4(aq) + 8H+ + 5e- → Mn2+(aq) + H2O(l) industry preparaion electrolysis on brine (Discussed in chapter 11 to make sodium hydroxide) Reminder isolated by electrolysis of brine:Anode: water is reduced to hydrogen and hydroxide 2H2O(l) + 2 e- → H2(g) + 2 OH-(aq)Cathode: Chloride oxidixed to chlorine2Cl-(aq) → Cl2(g) + 2 e-

Halogens

Chlorine isolated in 1774. Identified as new element in 1810 Sponges treated goiter, but active ingreedient iodine was not identified until 1819.Today we use iodized salt (KI is the source of iodine.) Bromine was discovered in 1817 and in 1829 the three eleements Cl, Br, and I were one of the first elemental triads by Dobereiner. Reactive fluorine was last to be isolted 1886 and many died from HF poisoning trying to isolate it including the discoverer, Moissan, who won the Nobel Prize for isolating fluorine.

Chlorine Oxyacids and Oxyanions

Chlorine oxyacids (oxidation state +1, +3, +5, +7 Acids strength increases with number of oxygens: HClO (very weak, Ka = 2.9 x 10-8) HClO2 (weak, Ka = Ka = 1.1 x 10-2) HClO3 (strong) HClO4 (very strong) Predominate species in solution for chlorooxyacids as a function of pH, Hypochlorous acid (HClO) and hypochlorite ion (ClO-) Reminder: chlorine in water produces hypochlorous acid.H2O(l) + Cl2(g) → HCl(aq) + HClO(aq) Weak acid HClO means solution of its conjugate base (ClO-) are very basic Both HClO and ClO- are oxidizing agents. HClO is stronger, and products differ 2HClO(aq) + 2H+ + 2 e- → Cl2(g) + 2H2O(l) ClO-(aq) + H2O(l) + 2 e- → Cl-(g) + 2OH-(aq)

Group Trends for Noble Gases

Colorless, odorless monotaomic gases. Only dispersion forces. Very low boiling and melting points.Smooth trend increasing with size. Densities reflect the fact that the gases have same number of particles per volume and the size increases down the group. Argon is most abundant due to decay of radioactive potassium-40. (decays by electron capture, described later) Until 1962, only compounds were clathrates.It is thought Kr and Xe which should be in the atmosphere of Saturn's large moon, Titan, is not detectable because those gases are in clathrates. Since the early 60s compounds have been formed with Kr (a few), Xe (extensive), and Rn (hard to work with due to radioactivity)

Deuterium

D forms stronger bonds than H. Electrolyzed water is richer in D2O. D2O is called heavy water. mp. 3.8 °C and bp. 101.4 °C D2O: solvent, in NMR, and isotopically labeling Deuterium oxide is used widely as a solvent so that the hydrogen atoms in solute molecules can be studied without their properties being "swamped" by those in the aqueous solvent. Greater energy difference in the "water" vs. "dihydrogen" means right side of the equilibrium is favoredHD(g) + H2O(liq) ⇄ H2(g) + HOD(liq)

Iodide has some unique chemistry

Diodine forms a blue complex with starch. formation of triiodide in the presence of diiodine. I-(aq) + I2(aq) → I3- (a linear ion, soluble in water) Iodide (I-) can be titrated in a redox reaction with iodate: IO3-(aq) + 5I-(aq) + 6H+(aq) → 3I2(aq) + 3 H2O(l) Iodine (I2) can be titrated in a redox reaction with thiosulfate: I2(aq) + 2S2O32- → 2I-(aq) + S4O62-

Ionic halides are prepared in several ways:

Direct combination of elements 2Co(s) + 3F2(g) → 2CoF3(s) Direct reaction with gaseous hydrogen halides:Co(s) + 2HF(g) → 2CoF2(s) + H2(g) Difluorine is a stronger oxidizing agent than hydrogen fluoride so it produces a higher oxidation state (3+) Reaction of metal oxides with aqueous hydrohalic acids yields hydrated compounds MgO(s) + 2HCl(aq) + 6H2O(l) → MgCl2(s)·6H2O(aq) This compund is not dehydrated by heating. It decomposes to Mg(OH)Cl:MgCl2(s)·6H2O(s) → Mg(OH)Cl(s)+ HCl(g) + 5H2O(aq) The anhydorus compound is obtained be dehydrating with thionyl chloride. MgCl2(s)·6H2O(s) + SOCl2(l) → MgCl2(s) + SO2(g) + 12HCl(g)

A Brief History of Noble Gas Compounds

Eight valence electron. eight bonds? 1924, Antropoff Prediction of oxides and fluorides 1933, Pauling Possible first preparation? Yost and Kaye Real progress. Neil Bartlett (1962) Worked with O2+ [PtF6-] O2 and Xe had similar ionization energies. Successfully prepared "Xe+ PtF6-". Probably actually was XeF+Hoppe in Germany argued through thermodynamic cycles that Xe compounds should exist.A few weeks after Bartlett, he prepared XeF2

Contrast of fluorine vs. chlorine

F-F bond is weaker than other halogens, but Fluoride ion forms strong lattice energy, thus fluoride are very stable as ionic compounds. Lattice energies of NaX. High charge density F- has a higher than expected lattice energy. Two factors: 1) weak F-F bond. High charge density of small F- ion. Fluoride is small and a good oxidizer there are usually more fluorides in the highest oxidation state than chlorides. Higher fluorides occur covalent compounds too. SF6 vs SCl2 NF3 is more stable than NCl3 (described in thermo chapter) F-X and F-CL bonds. heteronuclear F-X are always stronger. Polar covalent.

Fluorine

Fluorine is the most reactive element. Reacts wih every elelement but He, Ne, and Ar. In water Fluorine oxidizes water and is reduced:F2(g) 2e- → 2F-(aq)2H2O(l) → 4H+(aq) + O2(g) + 4e- Potential is very positive (favored) It can be understod in terms of favorable formation of F- anode (oxidation): 2F-(aq) → F2(g) + 2e-cathode (reduction): 2H+(aq) + 2e- → H2(g) A large use of Fluorine is used to make SF6, a colorless unreactive gas used in electrical devices for insulation. Another large use of Fluorine is used to make UF6 Step1: UO2(s) + 4HF(aq) → UF4(s) + 2 H2O STEP 2: UF4(g) + F2(g) → UF6(g) UF6 is used to separate the isotopes of uranium U-235 (fissionable) from U-238 for nuclear reactors. A series of centrfuges are used.

Fluorine

Fluorine reacts with every element but He, Ne, and Ar. In water Fluorine oxidizes water and is reduced:F2(g) + 2e- → 2F-(aq)2H2O(l) → 4H+(aq) + O2(g) + 4e- F2 is a stronger oxidizing agent than O2 The strong oxidizing potential of Fluorine can be understood in terms of favorable formation of F-(aq) ΔH of Formation of F-(aq) and Cl-(aq) Electrolysis cell to produce F2 from KF/HF (1:2) electrolyte anode (oxidation): 2F-(aq) → F2(g) + 2e-cathode (reduction): 2H+(aq) + 2e- → H2(g) A large use of Fluorine is to make SF6, a colorless, unreactive gas used in electrical devices for insulation. Adam from 'Mythbusters' demonstrating his voice in helium and sulfur hexafluoride. Another large use of Fluorine is used to make UF6Step 1: UO2(s) + 4HF(aq) → UF4(s) + 2 H2OStep 2: UF4(g) + F2(g) → UF6(g) UF6 is used to separate the isotopes of uranium U-235 (fissionable) from U-238 for nuclear reactors.

Ionic Halides

For a given cation, the chloride, bromide, and iodides are usually soluble,but the fluorides are often insoluble. Ca2+ for example Because HF is a weak acid, Flouride ion is a weak base. Souble ionic fluorides are basic. F-(aq) + H2O(l) → OH-(aq) + HF(aq)

Trihydrogen ion

Found in interstellar space Cosmic ray knocks off and electronH2(g) + [cosmic ray(1), hν] → H2+(g) + e- + [cosmic ray(2), hν] the cation collides with another dihydrogenH2+(g) + H2(g) → H3+(g) + H(g) The molecule is an example of a three center, two electron bond Also formed in the upper atmosphere of Giant planets (Jupiter, Saturn, Neptune, and Uranus) by collisions with solar winds (containing high energy electrons)H2(g) + e- → H2+(g) + 2e- (second step is the same.) The ion is destroyed by collision with CO molecules

Potassium Chloride

Found in lake beds impure separated by solubility of electrostaic isolation (ground powder and KCl gets a different charge) Only use fertilizer.

Hydrogen fluoride And hydrofluoric acid

HF has a much higher than expected boiling point due to hydrogen bonds. Chains of Hydrogen bond found in liquid or solid HF

Hydrogen fluoride and hydrofluoric acid

HF has a much higher than expected boiling point,due to hydrogen bonds Chains of Hydrogen bond found in liquid or solid HF Industrial synthesis of HF from calcium fluoride and sulfuric acid:CaF2(s) + H2SO4(liq) → 2HF(g) + CaSO4(aq)

Uses of noble gases - Helium

Helium is also found in underground deposits form decay of radioactive elements Alpha particles pick up two electrons:4He2+ + 2 e- → He US southwest has most of the world's supply underground. He in the atmosphere escapes into space. Hindenberg air ship. Originally designed for Helium. US embargo cause Germany to switch to hydrogen. While it is clear the hydrogen burned in the Hindenberg disaster, it is now thought the origin of the fire was ignition of aluminum paint flakes. Airships today have many uses besides the Goodyear blimp.Border patrol, lifting large objects, ecotourism, studying the canopy of the rain forest. Helium replaces nitrogen in scuba tanks to prevent the bends. Cooling scientific apparatus (MSU's NMR uses liquid helium to keep the magnet cool.)

Helium

Helium liquefies at 4.2 K at 1 atm To solidify helium requires 1 K and 2.5 Mpa pressure (25.6 atm). 4.2 K → Helium I, regular liquid 2.2 K → Helium II, an unusual liquidIt is a good thermal conductorIt's viscosity = 0, will climb the walls of a container:Video of this effectHelium II's weird behavior is a quantum phenomenon Found in natural gas deposits from radioactive decay. alpha particles pick up electrons. Used in Blimps instead of flammable hydrogen. Replaces nitrogen in diving gases to prevent the bends

Helium

Helium was discovered in the spectrum of the sun. (1868, Helios = Greek for sun) Helium sounds like a metal. Helion ? was suggested. Never caught on Helium escapes earth's atmosphere. Helium is becoming rarer. Used in MRI machines. US has national helium reserves. Will it run out? Helium for cooling instruments (MSU NMR instrument)

Compounds of He, Ar, Kr

Hydorhelium(+1) from Hydrogen-tritium decay H-T(g) → [H-He]+ + e- Argon hydrofuoride H-Ar-F from irradiation of Ar and HF -255 °C. decomposes at -245 °C VSEPR 3 lone pairs = linear KrF2 from krypton and fluorine irradiation at -196 °:C. decomposes at -20 °C

Reactions of Hydrogen Gas

Hydrogen gas is not very reactive, partly because of the high H¬H covalent bond energy Dihydrogen does react with dioxygen. If hydrogen gas and oxygen gas are mixed and sparked, the reaction is explosive:

Nuclear Magnetic Resonance

Hydrogen has the most intense absorption of a magnetic field. Most studied by NMR The spin of a hydrogen nuclei may be aligned with the field (lower energy) or opposed to the field (higher energy) Different environments of surrounding hydrogens = slightly different energies Differences are approximately one millionth of the field, so NMR shifts = ppm (parts per million)

Hydrides

Hydrogen is slightly negative GeH4 B2H6These compounds are usually pyrophoric they burst into flame in oxygen from airSnH4(g) + 2 O2(g) → SnO2(s) + 2H2O(liq) Metallic hydrides are formed by transition metals which are metals that absorb hydrogen and form compounds with formulas like (Ti4+)(H-)1.9(e-)2.1 Other compounds can freely absorb and release hydrogen Ni5Li for example Metal hydrides are used in nickel hydride batteries found in computers.These combine metals in an alloy such as:TiFeZnMn2LaTi5Mg2Ni Best combinations are: TiNI2 and LaNi5 Anode (oxidation of Ni2+ to Ni3+): Ni(OH)2(s) + OH-(aq) → NIO(OH)(s) + H2O(liq) + e-Cathode (reduction of water): [Ni-alloy]- + H2O(liq) + e- → [Ni-alloy]H- + OH-(aq)Cathode features reversible absorption of hydrogen.

Interhalogen Compounds and Polyhalides

Known Interhalogen compounds. X is heavier than Y. (-) indicates compound does not exist Linear ClF, BrF, BrCl, IF, ICl, IBr T-shaped ClF3, BrF3, BrCl3, IF3, ICl3, IBr3 Square Pyramid ClF5, BrF5, IF5 Pentagonal Pyramid IF7 structure of IF7, only I is big enough for 7 fluorines Prepared by stoichiometric combination of elements Sometimes used as easier to handle chlorinating agents, but may produce different oxidation states V(s) + 2Cl2(g) → VCl4(s) 2V(s) + 6ICl(s) → 2VCl3(s) + 3I2(s) ICl adds across double bonds in fats, and is used to quantitate degree of unsaturation. Only industrially important compound is ClF3 Used to fluorinate U, Pu, and other metals in fission products in nuclear fuels.U(s) + 3ClF3 → UF6(l) + 3ClF(g)Pu(s) + 3ClF3 → PuF6(s) + 3ClF(g)The liquid UF6(s) (Boiling point 55.6 °C) can be distilled from the other solid fluorides. In water, the compounds hydrolyze to HY and HXO (X,Y = halogen, Y is more electronegative) Note: This is similar to the reaction Cl-Cl undergoes with water BrCl(aq) + H2O(l) → HCl(aq) +HBrO(aq) There are several interhalogen cations and anions Interhalogen ions ICl2+ and ICl4- and molecular ICl3

Solubilities of Alkali metal: fluorides and iodides

Li + small ion hard acid F- small ion hard base good match, strong interaction, stays in solid Li + small ion hard acid I- large ion soft base poor match, weak interaction, goes into solution Cs+ large ion soft acid F- small ion hard base Poor match, weak interaction, goes into solution Cs+ large ion soft acid I- large ion soft base Good match, strong interaction, stays in solid

Reactions of chlorine

Like Fluorine reacts with many elements With iron, unusual high Fe 3+ oxidation state in formed 2Fe(s) + 3Cl2(g) 7rarr; 2FeCl3(s) Likewise with phosphorus, unusual high P 5+ oxidation state in formed 2P(s) + 5Cl2(g) 7rarr; 2PCl5(s) With organics the characteristic reaction is addition across double bonds to form 1,2-dichlorides.Example ethylene to 1,2-dichloroethane H2C=CH2(g) + Cl2(g) → Cl-CH2-CH2-Cl(g) Chlorine dissolved in water can act as a bleach First it react with water to produce an equilibrium mixture of HCl and HClO At equilibrium, the ratio is 2:1 (Cl2:HCL + HCLO) H2O(l) + Cl2(g) → HCl(aq) + HClO(aq) The active bleaching agent is created by the dissociation of HClO: HClO(aq) + H2O(l) → H3O+(aq) + CLO-(aq)

Covalent Halides

Most are low boiling gases or liquids Table 17.8 - Boiling points of boron halides Many are made by direct combination of the elements,stoichimometry can determine the product:Excess P: 2P(s) + 3Cl2(g) → 2PCl3(g)Excess Cl2: 2P(s) + 3Cl2(g) → 2PCl5(g)2Al(s) + 3Cl2(g) → 2AlCl3(g)Video of Aluminum reacting with chlorineNEXTMost react violently with waterSCl4(g) + 2H2O → SO2 + 4HCl2AlCl3(g) + 3H2O → Al2O3(s) + 6HCl(g) (at 300 °C) Metal halides in high oxidation states have covalent bonding.TiCl4(l) + 2H2O(l) → TiO2(s) + 4HCL(g) Note SF6 should react with water according to ΔH = - 460 kJ/mol, but it is kinetically stable.

Uses of chlorine dioxide

NaClO = Clorox bleach, bleaching wood pulp, disinfectant, unstable as a solid Ca(ClO)2 - Stable solid, solid state bleach and disinfectant used in dairies, breweries, food processing, and bottling plants. NaClO should not be used with acidic cleansers because Chlorine in generated.HClO(aq) + HCl(aq) → Cl2(g) + H2O(l) chlorite (ClO2-) - of little use chlorate (ClO3-)Prepared by bubbling chlorine through hot aqueous sodium hydroxide. 3Cl2(g) + 6NaOH(aq) → NaClO3(aq) + 5NaCl(aq) + 3H2O(l) NaClO3 is used to make ClO2(l)KClO3 - is a good oxidizer, used in fireworks and matches. Chlorates decompose on heating to chlorides and oxygenUncatalyzed goes through a perchlorate intermediate, KClO4 Catalyzed by MnO2 avoids the explosive perchlorates Perchloric acid and perchlorates Strong oxidizers and a strong acid, care must be used in their handling. Pure acid is very reactive, organic such as wood or paper burst into flame on contact Ammonium perchlorate is used as a solid rocket fuel 6NH4ClO4(s) + 8Al(s) → 4Al2O3 + 3N2(g) + 3Cl2(g) + 12H2O(g) On 5/4/1989 a fire at a ammonium perchlorate plant wiped out half of the US supply Four explosions at the PEPCON rocket fuel plantUpon heating the ammonium perchlorate explodes according to:2 NH4ClO4(s) → N2(g) + Cl2(g) + 2O2(g) + 4H2O(g)

Potassium

Natural potassium contains 0.012 % radioactive 40P Test for potassium. hexanitrocobalt(III). sodium compound is soluble.3K+ + [Co(NO2)6]3- → K3[Co(NO2)6](yellow precipitate)tetraphenyl borate can also be used to precipitate potassium. Isolation of potassium. electrochemically: too dangerous. chemically at 850 °C: safer.Na(l) + KCl(l) → NaCl(l) + K(g) Interesting fact. Gaseous potassium is YELLOW .

Argon

Oxygen and Nitrogen are not the full components of air (1775) Argon is discovered and characterized by visible spectroscopy (1880s) Argon is used for inert atmosphere Neon lights. Tube with neon. High voltage discharge. Emission spectra is shown. Other gases may be used as well.

Oxides

The reactions with oxygen differ Lithium is "normal"2Li(s) + O2 → Li2O(s) Sodium form the dioxide(2-) or peroxide, O22-2Na(s) + O2 → Na2O2(s) Potassium, Rubidium, and cesium form dioxide(1-) or superoxide O2-K(s) + O2 → KO2(s) peroxide, O22-, is isoelectronic with F2 and is diamagnetic However the superoxide, O2-, is paramagnetic Bond lengths O2, 121 pm (double bond) O2-, 133 (1.5 bond) O22-, 149 (single bond) The oxide all react with water to form the hydroxides.Li2O(s) + H2O(l) → 2LiOH(s) additional products are formed with the sodium (hydrogen peroxide ) and potassium (hydrogen peroxide and oxygen) oxidesNa2O2 + 2H2O(l) → 2NaOH(s) + H2O2(aq)2KO2(s) + 2H2O(l) → 2KOH(s) + H2O2(aq) + O2(g) Potassium superoxide is used space capsules and submarines to genertate oxygen4KO2+ 2CO2 → 2K2CO3(s) + 3O2(g)

Uses of sodium carbonate

Preparation of glass at high temperatures (top use):Na2CO3(l) + xSiO2(l) → Na2O·xSiO2(l) + CO2(l) "softening" hard water by removing alkaline earth metal cations as calcium ion:CO32-(aq) + Ca2+ → CaCO3(s)

Xenon Fluorides

Prepared by direct combination. Xe(g) + F2(g) → XeF2(s) Xe(g) + 2F2(g) → XeF4(s) Xe(g) + 3F2(g) → XeF6(s) Reactions with water 2XeF2(s) + 2 H2O(l) → 2Xe(g) + O2(g) + 4HF(l) XeF6(s) + H2O(l) → XeOF4(l) + 2HF(g) further hydrolysis occurs XeOF4(l) + 2H2O(l) → XeO3(s) + 4HF(g) Fluorination agents XeF2 can add F across double bonds XeF2 + R2C=CR2 → FR2C-CR2F + Xe Xenon fluorides may be used to produce high oxidation state fluorides:XeF4(s) + 2SF4 → Xe(g) + 2SF6(g)

Biological Aspects for Noble Gas

Radon formed by radioactive decay in the earth seeps up and may enter houses. As houses become more sealed, radon danger increases. Radon gas may be breathed into the lungs, radon decays to a metal such as Po-218, the metal is stuck and radiation causes lung cancer. The problem was discovered when a nuclear worker set off a radiation detector as he entered the facility Chlorine isolated in 1774. Identified as new element in 1810 Sponges treated goiter, but active ingredient, iodine, was not identified until 1819.Today we use iodized salt (KI is the source of iodine.) Bromine was discovered in 1817 and in 1829 the three elements Cl, Br, and I were one of the first elemental triads by Dobereiner. Reactive fluorine was last to be isolated 1886 and many died from HF poisoning trying to isolate it including the discoverer, Moissan, who won the Nobel Prize for isolating fluorine. All have odd atomic numbers, so few isotopes. 19F only one 127I only one 35Cl (76%) and 37Cl (24%) 79Br (51%) and 81Br (49%)

Ammonia Reaction

Raection of alkali metal in ammonia produces deep blue solutions containing solvated electron.Na(s) ⇔ Na+(NH3) + e-(NH3) This is a good reducing agent Evaporating the solvent initially preoduces a bronze colored liquid metal that decomposes to to sodium amide:2Na+(NH3) + 2NH3(l) + 2e-(NH3 → 2 NaNH2(NH3) + H2(g)

Uses of noble gases

Relative abundancies in the atmosphere of the noble gases

Sodium

Seawater is 3% sodium chloride. Most is isolted from rock salt mining From sewater evaporation Used in manufactoring more than any other mineral (150 million tonnes a year)

Group Trends - Alkali Metals

Shiny surface, silver color, heat and electricity conduction similar to most metals They are soft, low melting, and low density not like other metals Low melting points and low Enthalpy of atomization = weak metallic bonds Typical reactions of alkali metals:Reaction of Li with oxygen4Li(s) + O2(g) → 2Li2O(s)Reaction with halogens2Na(s) + Cl2(g) → 2NaCl(s)Reaction with water2K(s) + 2H2O(l) → 2KOH(s) + H2(g)

sodium hydrogen carbonate

Sodium carbonate is formed by bubbling carbon dioxide through saturated solutions of sodium carbonate.Under these conditions, the product precipitates out.Na2CO3(aq) + H2O(l) + CO2(g) → 2NaHCO3(s) the solid sodium hydrogen carbonate reverses the reaction when heated.Release of CO2 can be use in fire extinguishers or as a leavening ingrdeient in baking (top use).2NaHCO3(s)→ Na2CO3(s) + H2O(l) + CO2(g)

Reactions of hydrogen

Spontaneous reaction with oxygen is explosive.2H2(g) + O2(g) → H2O(g) This reaction is unfavorable in entropy, but the enthalpy of the strong O-H bonds makes up for this as is seen in the Born-Haber cycle Rate of reaction with halogens decreases down the group. Fluorine is explosive. Iodine is very slow.H2(g) + F2(g) →2HF(g) Reaction with nitrogen is industrially important and is slow without a catalyst.3H2(g) + N2(g) ⇆ 2NH3(g) At high temperatures, hydrogen can reduce metal ores to the elements.Fe2O3(s) + 3H2(g) → 2Fe(s) + 3H2O(g) Hydrogen is used to hydrogenate alkene and alkynes usually with a palladium catalyst. Partially hydrogenated vegetable oils = Crisco are made this way.H2C=CH2 + H2(g) → H3C-CH3(g) In the laboratory small amounts of hydrogen can be made by the reaction of acids with metals:2HCl(aq) + Zn(s) → ZnCl2(aq) + H2(g) he metal + acid route is too expensive for large scale production, so methane is converted to hydrogen in the steam reforming process:CH4(g) + H2O(g) → CO(g) + 3H2(g)The CO is hard to separate from the hydrogen, so it is further reacted with water to yield CO2CO(g) + H2O(g) → CO2(g) + H2(g)The CO2 can be removed by bubbling the mixture through aqueous potassium carbonate to trap the carbon dioxide as the bicarbonate.K2CO3(aq) + CO2(g) + H2O(g) → 2KHCO3(aq) When very pure hydrogen is needed, it can be generated by electrolysis. Hydrogen forms at the cathode:2H2O(l) + 2e- → 2OH-(aq) + H2(g)and oxygen forms at the anode:3H2O(l) + → 2H3O+(aq) + 1/2O2(g) + 2e-Net reaction:H2O(l) → H2(g) + 1/2O2(g)

Chlorine Chemistry

The higher the oxidation state of Cl, the better an oxidizing agent it is. Species have higer oxidiziing abilty in acid solution that basic. Note isoelectronic phosphate and sulfate are not good oxidizers. Cl- is most stable state

Overview of Chlorine chemistry

The higher the voltage (free energy in table) = better an oxidizing agent . Better oxidizing ability in acid solution that basic for a given oxidation number. Note: isoelectronic phosphate and sulfate are not good oxidizers. Stability of various Cl containing species Cl- is most stable state

Solubilities of Alkali Metal Compounds

The ionics are usually water soluble, but solubilities vary over a wide range: Solubilties are explained by considering Enthalpy and Entropy Enthalpies of breaking the lattice and hydrating the ions nearly cancel out to zero: The enthalpy varies from non-favorable for NaF to very favorable for LiI

Uses of Sodium Metal

Uses of sodium metal Most used alkali metal in industry Isolation of rarer metals such as titanium4 Na(s) + Ti4(l) → Ti(s) + 4 NaCl(s) Outside of the US Na/Pb alloy is employed to make tetraethyl lead to add to gasoline4 Na/Pb(s) + 4CH3-CH2Cl(g) → (CH3-CH2)4Pb(l) +3Pb(s) + 4NaCl(s)

Lithium

Very low density. Useful in alloys where low density is desired Reacts with oxygen in air4 Li(s) + O2(g) → 2 Li2O(s) higher charge density allows formation of one of the few nitrides,but this compound is not stable in the presence of water6 Li(s) + N2(g) → 2 i3N(s) Li3N(s) + 3 H2O(l) → 3 LiOH(s) + NH3(g) Very strong reducing agent, will eat glass Reaction with water is spontaneous, but kinetically slow

Hydrochloric acid

Very soluble. Concentrated HCl is 38% by mass and is 12 M. Strong acid 100% ionized. Because Cl- has little oxidizing power, HCl is the best non-oxidizing acid. Industrial prep as a by-product of organic chlorination dfCH4(g) + 2Cl2(g) → CCl4 (g) + 4HCl(g)

Hydrochloric acid

Very soluble. concentrated HCl is 38% by mass ansd 12 M. Strong acid 100% ionized. Because Cl- has little oxidizing power, HCl is the best choice for a non-oxidizing acid is needed. Industrial prep as a by-product of clorination CH4(g) + Cl2(g) → CF4 (g) + HCl(g)

Water & Hydrogen Bonding

Water has a long liquid range liquid ranges of group 16 hydrides Water has an open crystal structure so ice is less dense than liquid water Water forms cage like clatharates with noble gases, carbon dioxide, and hydrocarbons like methane Carbon dioxide clatharates may isolate CO2, a greenhouse gas

chlorine dioxide

Water soluble, explosive, yellow gas that condenses to Red liquid at 11 °C Odd electron species, but does not dimerize. Cl=O bond distance about that for a double bond(140 pm, 170 pm = a single bond) A Lewis structure for ClO2,

Hydroxides

White solids, only lithium is hydrated All absorb moisture from the air All absorb CO2 to form the carbonate 2NaOH(s) + CO2(g) → Na2CO3(s) + H2O(l) NaOH is the most common source of hydroxide ion in water. KOH is better to use in organic chemistry due to higher solubility in organic solvents. isolated by electrolysis of brine:Anode: water is reduced to hydrogen and hydroxide2H2O(l) + 2 e- → H2(g) + 2 OH-(aq)Cathode: Chloride oxidixed to chlorine2Cl-(aq) → Cl2(g) + 2 e- Reaction is done in a diaphragm cell with solution of sodium hydroxide is evaporates to isolate the solid.

Xenon Oxides

XeO2 is not stable. It disproportionates to Xe(g) and XeO3 The structure of XeO2 is a polymer of square planar Xe bridges by oxygen. Xe may substitute for silicon in silicates in deep earth. Both have tetrahedral bonds to oxygen.

Xenon Oxides - XeO3

XeO3 is a colorless explosive solid. Good oxidizer, but kinetically slow XeO3 reacts with base to form hydrogen xenate which decomposes to perxenate: XeO3(s) + OH-(aq)→ HOXeO3-(aq)Note I wrote the formula differently 2HOXeO3-(aq) + 2OH-(aq) → XeO64-(aq) + Xe(g) + O2(g) + 2H2O(l)(Note: the second equation is wrong in the book. Wrong formula for first reactant.) XeO64-can be crystalized as ionic salts with alkali metals and alkaline earth ions. Xenon oxides and xenon oxyanions are great oxidizers XeO64- is like IO65- Redox example: XeO64-(aq) +5H+(aq) + 2e- → HOXeO3-(aq) + 2H2O(l) Above strong enough to oxidize Mn2+ to Permanganate MnO4-

Tritium

a radioactive isotope with a half-life of about 12 years being formed by the impact of cosmic rays on atoms in the upper atmosphere. Tritium is formed when cosmic rays hit nitrogen. Used as Medical tracer. Tritium is generated by the nuclear reaction for use in hydrogen bombs.6Li + 1n → 4He + 3T Hydrogen isotopes have the largest relative mass ratios → affects reaction rates and equilibria

Uses of Lithium

auto greases such as lithium stearate, C17H35COOLiCH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH--CH2-COOLi Organometallic reagent like n-butyl lithium, LiC4H9, a very strong base. Lithium batteries advantages: light, high reduction potential, common in computers other electronics. in the future--> automobile bateriesCommon recheargable battery Anode: LiCoO/2: Co3+ is oxidized to Co3+ with release of Li1+LiCoO2(s) → Li(1-x)CoO2(s)2 + xLi+(solv) + xe-Cathode: graphite: Lithium ions migrate in an organic liquid to graphite and are reduced to litium metalC(s) + xLi+(solv) +xe- → LixC(s) Recharging: reverses the two reactions above.There are other lithium batteries using manganese(IV)oxide, vanadium(V)oxide for the anode More complicated batteries use thionyl chloride.anode: Li(s) → Li+(solv) + e-cathode: SOCl2(l) + 4e- → 4 Cl-(solv) + SO2(solv) + S(solv)irreversible, so not rechargeable, due to insoluble LiCl formation.

Isolation of sodium is the Down's process which electrolyzes smolten sodium chloride.

graphite anode: 2 Cl- → Cl2(g) + 2e- (chlorine gas exits cell) steel anode: Na+ + e- → Na(s) (sodium floats to top and is drawn off) CaCl2 is added to lower melting point 778 °C for NaCl and 580 °C for 2:1 CaCl2:NaCl Steel gauze separates anode from cathode sections

Properties of Hydrogen

hydrogen has an electronegativity higher than those of the alkali metals and lower than those of the halogens, Hydrogen could be placed in the table in three possible locations:In group 1, in group 17, or by itself Dihydrogen, H2, is odorless, colorless, mp. -259 °C, bp. -253 °C, and has a strong bond of 436 kJ/mol. Hydrogen's strong bond makes it somewhat unreactive, but it does have a few important reactions:

Uses of hydroxides

industrial organic syntheses 30% industrial inorganic syntheses 20% pulp and paper 20% many "other" ways 30% Base in laboratories Household drain cleaner2AL(s) + 2OH- + 6H2O → 2[Al(OH)4] + H2(g) (hydrogen bubble help clear drain) Many food uses: potatoes skin softening, Olive prosessing, Grits, pretzels, chocolate.

Biological Aspects for alkali metals

sodium and potassium are required in the diet. sodium about 1 g a day. Alkali metals are balance charge in proteins. Alkali metal maintain osmotic pressure. The difference in concentration is the source of electrical potential in the body. Antibiotics often have holes that span membrance and allow a certain ion to pass

valence isoelectronic

species have the same number of valence electrons but different numbers of total electrons

steam re-forming process

the endothermic reaction of natural gas (methane) with steam at high temperatures gives carbon monoxide and hydrogen gas. It is diffi cult to separate the two products because the mixture must be cooled below 2 205 8 C before the carbon monoxide will condense. To overcome this problem and to increase the yield of hydrogen gas, the mixture is cooled, additional steam is injected, and the combination is passed over a different catalyst system.

Ammonium as a pseudo Alkali Metal Ion

the radius of ammonium ion (NH4+, 151 pm, 1.51 Å) has is similar to that of potassium ion (K+, 152 pm, 1.52 Å) NH4+ can replace K+ in cryswtal structures. ammonium chloride High temperature has CsCl structure and a NaCl structure at low temperatures. Ammonium precipitates with the reagent that tests for potassium: o3NH4+ + [Co(NO2)6]3- → (NH4+)3[Co(NO2)6](yellow precipitate) There are some differences:Heating alkali metal nitrates gives the nitites:2NaNO3(s) → 2NaNO2(s) + O2(g)but heting the ammonium compound produces dinitrogen oxide and destroys the ammonium ion:NH4NO3(s) → N2O(s) + H2O(g) neutral NH4" can not be isolated.

Hydrogen Isotopes

where isotopic mass differences are so large. The difference in isotope masses can affect reaction rates and the position of equilibria. he three main isotopes of hydrogen are normal hydrogen protium, deuterium and tritium