BiologyandSociety:Chapter2FluorideintheWater•FluorideEssential–IsacommoningredientinEarth’scrust–HelpsmaintainhealthyteethChemistry•FluoridepreventscavitiesbyForBiology–Affectingthemetabolismoforalbacteria–PromotingthereplacementoflostmineralsonthetoothsurfaceSOMEBASICCHEMISTRYMatter:ElementsandCompounds•Whychemistry?Ithoughtthiswasabiology•Matterisanythingthatoccupiesspaceandhascoursemass.•Well,takeanybiologicalsystemapart,andyou•MatterisfoundontheEarthinthreephysicaleventuallyendupatthechemicallevel.states:–Indeed,yourbodyisonebigcontainerof–Solidchemicalsundergoingacontinuousseriesofchemicalreactions–Liquid–GasFigure2.16•Matteriscomposedofchemicalelements.C12–Elementsaresubstancesthatcannotbebrokendownintoothersubstances.HHeLiBeBCNOFNe–Thereare92naturallyoccurringelementsNaMgAlSiPSClAronEarth.KCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXe•EachelementhasitsownsymbolCsBaLaHfTaWReOsIrPtAuHgTlPbBiPoAtRn•AlloftheelementsarelistedintheperiodicFrRaAcRfDbSgBhHsMtUunUuuUubUuqUuhUuotable.CePrNdPmSmEuGdTbDyHoErTmYbLuThPaUNpPuAmCmBkCfEsFmMdNoLr1•Twenty-fiveelementsareessentialtolife.•Fourelementsmakeupabout96%oftheweightofthehumanbody:LeadPbCopperCu–Oxygen(O)–Carbon(C)–Hydrogen(H)–Nitrogen(N)MercuryHgFigure2.1CarbonC:18.5%•TraceelementsOxygenO:–Occurinverysmallamounts65.0%CalciumCa:1.5%PhosphorusP:1.0%–However,theyareessentialforlifePotassiumK:0.4%SulfurS:0.3%SodiumNa:0.2%–Thereare14oftheseelementsChlorineCl:0.2%MagnesiumMg:0.1%HydrogenH:–Examples:9.5%Traceelements:lessthan0.01%BoronBManganeseMn–Iodine(I)ChromiumCrMolybdenumMoNitrogenN:CobaltCoSeleniumSe3.3%CopperCuSiliconSi–Fluorine(F)FluorineFTinSnIodineIVanadiumVIronFeZincZn–Iron(Fe)Figure2.2•Iodineisanessentialingredientofhormoneproducedbythethyroidgland(intheneck)•Elementscancombinetoformcompounds.•Iodinedeficiencycausesgoiter.–Compoundsaresubstancesthatcontaintwoor