Principles of Chemistry II © Vanden BoutThe rest of the SemesterAll of ChemistryTodayGroups 1-IVPrinciples of Chemistry II © Vanden BoutThings everyone should knowGet to know the chemistry of the elementsHow is each element found in natureReactions involving compounds with those elements Practical uses of those compoundsPrinciples of Chemistry II © Vanden BoutFirst what is the most abundant element in the Universe?A. HydrogenB. HeliumC. OxygenD. SiliconE. IronPrinciples of Chemistry II © Vanden BoutPrinciples of Chemistry II © Vanden BoutWhat about in our part of the universe?Principles of Chemistry II © Vanden BoutFirst what is the most abundant element on the Earth's crust?A. HydrogenB. HeliumC. OxygenD. SiliconE. IronPrinciples of Chemistry II © Vanden BoutPrinciples of Chemistry II © Vanden BoutMonahans Sand Dune's State ParkSand is SiO2Principles of Chemistry II © Vanden BoutElemental Makeup of you?A. HydrogenB. HeliumC. OxygenD. SiliconE. IronPrinciples of Chemistry II © Vanden BoutNote by atoms, Hydrogen is the most abundantPrinciples of Chemistry II © Vanden BoutPeriodic TableGrouped by "common chemistry"1. Chemistry dominated by the number of valence electrons (this is the "group")2. Compounds that are formed nearly always achieve nobel gas like structures (octet rule)3. Periodic Trends (radius, ionization energy,...)4. The 2nd row is very special. Overlapping 2p orbitals leads to pi bonding. Highly electronegative atoms lead to H-bondingPrinciples of Chemistry II © Vanden BoutPeriodic TableGrouped by "common chemistry"5. Most elements for a stable compound withthemselves making a nobel gas structure as with metallic bonding or network solids or small molecules (N2, P4,...)6. Most everything makes a hydride from ionic hydrides like NaH to covalent H2O to HCl7. Most everything makes an oxide. Basic oxides on the left (MgO), acidic on the right (CO2).Principles of Chemistry II © Vanden Boutvery smallonly a single1s electrongreater electronegativity than other group 1HydrogenIn a group of its ownPrinciples of Chemistry II © Vanden BoutHydrogenelectronegativity of 2.1(nearly exactly the same as carbon)might lose an electron (+1 oxidation state)might gain an electron (-1 oxidation state)2K(s) + H2(g) 2KH(s)2H2(g) + O2(g) 2H2O(g)Principles of Chemistry II © Vanden BoutPrinciples of Chemistry II © Vanden BoutWho cares about hydgrogen2H2 + O2 2H2Oreaction = 2x(enthalpy of formation of water) -475 kJ mol-1Most energy per mass of any reactionPrinciples of Chemistry II © Vanden BoutThe problem is there is no H2Where to get it?CH4(g) + H2O(g) CO(g) + 3H2(g)Steam reforming of methane (1000°C, Ni Catalyst)Water gas shift (130°C)CO(g) + H2O(g) CO2(g) + H2(g)Principles of Chemistry II © Vanden BoutOther fun with H2H+ can oxidize metalsZn + 2H+ Zn2+ + H2Principles of Chemistry II © Vanden BoutOther fun with H2CuO + H2 Cu + H2OH2 can reduce oxidesPrinciples of Chemistry II © Vanden BoutPrinciples of Chemistry II © Vanden BoutGroup 1 metalsAlkali MetalsAll have a nS1 electronic configurationVery low ionization energyBehave like a metal (easily oxidized)From +1 ion alwayslow boiling and melting pointsreact violently with water (and most anything else)from basic hydride and oxidesPrinciples of Chemistry II © Vanden Bout2Na + 2H2O 2Na+ + 2OH- + H2(g)Is this reaction exothermic?1. Yes2. NoPrinciples of Chemistry II © Vanden BoutBest Reducing AgentsPrinciples of Chemistry II © Vanden BoutGroup 1 elements will react with nearly anything2Na(s) + Cl2(g) NaCl(s)3Li(s) + N2(g) 2Li3N(s)4Na(s) + O2(g) 2Na2O(s)reactions with airPrinciples of Chemistry II © Vanden BoutHydrides and oxides are basicNa2O(s) + H2O(l) 2NaOH(aq)Nucleophilic (wants nuclei) Electron richNaH(s) + H2O(l) 2NaOH(aq) + H2(g)H in -1 oxidation state (can deprotonate nearly anything)Principles of Chemistry II © Vanden BoutWhere are they? Everywhere as ionsNa+, K+ are everywhere (Li+ because it has such a large charge density often makes insoluble compounds)Rb, Cs, Fr very little in the universeNa+ and K+ critical in biochemistryPrinciples of Chemistry II © Vanden BoutPrinciples of Chemistry II © Vanden BoutGroup II metalsAlkali Earth MetalsAll have a nS2 electronic configurationVery low ionization energyBehave like a metal (easily oxidized)From +2 ion alwaysreact with water (and most anything else)Principles of Chemistry II © Vanden BoutDifference compared to group 1+2 ions have a very high charge densityOften they make insoluble compoundsPrinciples of Chemistry II © Vanden BoutA. MagnesiumB. CarbonC. They are the sameWhich is easier to
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