H2 Chemistry Explanations

Atomicstructure● StatethedefinitionofatomicmassItistheratiooftheaveragemassofoneatomofanelementto1/12themassofone 12 Catom ● StatethedefinitionofisotopicmassItistheratioofthemassofoneatomofanisotopeofanelementto1/12themassofone 12 Catom ● GiveninformationabouttheN–ObondinNO3 - whyisitinaccuratetorepresentNO3 - ashavingdoubleandsinglebonds?N–OisoflengththatisintermediatebetweentheoreticalN–OandN=Obondlength,soinaccurate. ● SuggestthemixingandoverlapofatomicorbitalswhichaccountforthepartialdoublebondcharacterinN-Obond.1. Mixing2. Overlap3. Explainhowresonancearisesa. Continuousside-wayoverlap→pielectronsdelocalize→givesrisetoresonancestructure→partialdoublebondcharacter ● ExplainifthemoleculeNCCNispolarC—Nbondispolardipolemomentscanceleachotherbecauseatomsarearrangedlinearlynonetdipolemoment ● Howdoesid-idandpd-pdariseElectronsinelectroncloudmoverandomly→unevendistributionofelectroncloud→instantaneousdipole→inducedipoleinadjacentmolecule ● Bondangleingraphene(planar)is120 0 . ● WhyisSrdenserthanCaIncreaseinmassismoresignificantthanincreasedsizeofSr.Noneedtobringinstrengthofmetallicbonding. Redox● Ag2O+H2O2->2Ag+O2+H2O.ExplainwhyH2O2actsasRA.Oxygenappears2timesonthereactantside(disproportionation),sodon’tfocusono.s.OfO.Focusonotherreactant(Ag). Physical periodicity● ExplainwhysuccessiveI.E.increasesgenerally.[2m] 1) Numberofprotonsconstant,numberofelectronsdecreasing.2) Nuclearattractionincreases 1

● (Givendata)Stateandexplainthegroupnumberofelementxx.[2m] 1) ThereisalargespikefromwhichI.E.towhichI.E.2) TheXXthelectronisremovedfromtheinnerprincipalquantumshell/Therearexxvalenceelectrons ● CalculateenergyneededtoremovexxxmolesofelectronsTotalenergy=ionisationenergy*amtofelectronsCuzionisationenergyisenergyfor1moleofelectrons ● WhyionicradiiofarandomionandaTMionaresimilarTMion:highernuclearcharge,greatershieldingeffect,furtherawayfromnucleus.Butnuclearattractionissimilarcuz3delectronsprovidepoorshielding Chemical Bonding● Explaintheshapeofxxx. 1) Statenumberoflonepairsandbondpairs.2) ByVSEPRtheory,electronpairsareplacedasfarapartaspossibletominimisemutualrepulsion. ● Suggestabondangleofxxx. 1) Statenumberofloneandbondpairs.2) xxrepulsionislargerthanxxrepulsion(lplp>lpbp>bpbp)3) IfqnsayuseVSEPRtheory,statethatbyVSEPR,electronsareplacedasfarapartaspossibletominimiseinterelectronicrepulsion VSEPR:includesboth2and3 ● WhyisC–Cbondbtwsp2-sp3orbitalsstrongerthanbtwsp3-sp3orbitals Btwsp2-sp3:Covalentbondhashigher%ofscharacterMoreeffectiveorbitaloverlap Content:● CCl4andSiCl4aresimplemolecules!● strengthofcovalentbond:○ Bondorder:i. #oforbitalsoverlappedii. electrondensitybetweenbondingatomsiii. attractionbetweenbondingnucleiandsharedelectrons○ Effectivenessoforbitaloverlap:i. %ofscharacter inhybridorbital● “sp2-sp2overlapinXismoreeffectivethansp3-sp3overlapinYduetohigher%ofscharacterinhybridorbitals.” 2

ii. atomicsize ● WhycanAlCl3formdativebondstobecomeadimerAlatomhasemptyorbital,canacceptlonepairelectronsfromCl ● IntramolecularHbondOnlypossibleiftheringha