IONIZATION ENERGIES Figure 197 in textbook The more electrons in one shell the poorer the shielding is which equals a higher effective nuclear charge Electron Affinity The energy change that occurs when an electron is added to an isolated atom in the gaseous state Octet Rule Main group elements tend to undergo reactions that leave them with eight outer shell electrons That is main group elements react so that they attain a noble gas electron configuration with filled s and p sub levels in their valence electron shell Metals tend to have low ionization energies and low electron affinities they tend to lost one or more electrons Nonmetals tend to have high ionization energies and low electron affinities they tend to gain one or more electrons ex Sodium and Chlorine can react because sodium readily loses one electron and chlorine readily gains one electron Na Cl Na Cl BORN HABER CYCLE The sum of the energy changes for the five steps equals the net energy change for the overall reaction The most favorable step is the formation of solid NaCl from gaseous Na and Cl ions Lattice Energy The amount of energy that must be supplied to break up an ionic solid into individual gaseous ions Lattice energy increases up and left PROPERTIES OF ELEMENTS Alkali Metals Powerful reducing agents Metallic Bright silvery Malleable Good conductors of electricity Relatively soft Very reactive Occur only in salts Alkaline Earth Metals Reducing agents Metallic Bright silvery Relatively soft harder than 1a Not as reactive as 1a Occur only in salts
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