1035 Chapter 9 NTA.pdf - Chapter 9 Models of Chemical...

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Chapter 9Models of Chemical Bonding1
Bonding and Valence ElectronsWe are going to look at the formation of chemical bonds.Bonding is a result of atoms interacting with their valence electrons. Valence electrons can be:1. given away2. received3. shared2
Valence Electrons ReviewValence Electrons are the electrons involved in chemical reactions.Main group elements: all electrons with the highest n valueTransition metals: electrons with the highest n value, and d electrons in incomplete d sublevels. Cs: [Xe] 6s1one valence electronSi: [Ne] 3s23p2four valence electronsBr: [Ar] 4s23d104p5seven valence electronsSb: [Kr] 5s24d105p3five valence electrons3
Lewis Dot DiagramsWe use dots to represent valence electrons around an atom.4
Lewis Dot DiagramsFor a metal, the total number of dots in the Lewis symbol is the number of electrons the atom loses to form a cation.For a nonmetal, the number of unpaired dots equals 1. the number of electrons the atom gains to form an anion2. the number it shares to form covalent bonds5
Three Types of Bonding6Ionic BondingCovalent BondingMetallic Bonding
Bonding and Bond Energies1. Ionic Bonding 2. Covalent Bonding3. Bond Energy4. Polarity7
Ionic Bonding – Lithium FluorideLithium wants to be Helium.Fluorine wants to be Neon.Li: 1s22s1= [He] 2s1Li+: 1s2= [He]loses an electron to “be a noble gas”Li Li++ eIonization Energy = 520 kJ/molF: 1s22s22p5F: 1s22s22p6= [Ne]gains an electron to “be a noble gas"F + eFElectron Anity = -328 kJ/mol8
Ionic Bonding – Lithium FluorideLi Li++ eF + eF9
Ionic Bonding – Lithium FluorideThe ionic bond Li+F-1. Involves a complete transfer of an electron2. The electron is transferred from a metal to a nonmetal (cation to an anion)3. Ions are held together by the electrostatic attraction between oppositely charged ions.10

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