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Chapter 8 covalent bonding
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  • 1. 1“CovalentBonding”Ball-and-stick model
  • 2. 2Objectives–Explain the role and location ofelectrons in a covalent bond.–Describe the change in energy andstability that takes place as acovalent bond forms.–Compare covalent and ioniccompounds.
  • 3. 3Bonds are… Forces that hold groups ofatoms together and make themfunction as a unit. Two types:1) Ionic bonds – transfer ofelectrons (gained or lost; makes formula unit)2) Covalent bonds – sharing ofelectrons. The resultingparticle is called a “molecule”
  • 4. 4Molecules The simplest example of sharingelectrons is found in diatomicmolecules. For example, air contains oxygenmolecules, consisting of two oxygenatoms joined covalently (O2) Air also contains hydrogen molecules,consisting of two hydrogen atoms joincovalently (H2)
  • 5. 5How does H2 form? Both nucleus repel each other,since they both have a positivecharge (like charges repel).++(diatomic hydrogen molecule)+ +
  • 6. 6How does H2 form?++ But, the nuclei are attracted tothe electrons They share the electrons, andthis is called a “covalent bond”,and involves only NONMETALS!
  • 7. 7Covalent bonds Nonmetals hold on to their valenceelectrons. They can’t give away electrons to bond.–But still want noble gas configuration. Nonmetals get it by sharing valenceelectrons with each other = covalentbonding By sharing, both atoms get to countthe electrons toward a noble gasconfiguration.
  • 8. 8Energy and Stability Most individual atoms have low stability.– Remember, if an atom doesn’t have eightvalence electrons they are unstable. They become more stable when they are part ofa compound. Individual atoms also have higher potential(stored) energy. When atoms are bonded they are at their lowestpotential energy. The distance between two bonded atoms at theirlowest potential energy is the bond length
  • 9. 9Potential Energy
  • 10. 10Covalent bonding Fluorine has seven valenceelectrons (but would like to have 8)F
  • 11. 11Covalent bonding Fluorine has seven valenceelectrons A second atom also has sevenF F
  • 12. 12Covalent bonding Fluorine has seven valenceelectrons A second atom also has seven By sharing electrons…F F
  • 13. 13Covalent bonding Fluorine has seven valenceelectrons A second atom also has seven By sharing electrons…F F
  • 14. 14Covalent bonding Fluorine has seven valenceelectrons A second atom also has seven By sharing electrons…F F
  • 15. 15Covalent bonding Fluorine has seven valenceelectrons A second atom also has seven By sharing electrons…F F
  • 16. 16Covalent bonding Fluorine has seven valenceelectrons A second atom also has seven By sharing electrons…F F
  • 17. 17Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons… …both end with full orbitalsF F
  • 18. 18Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons… …both end with full orbitalsF F8 Valenceelectrons
  • 19. 19Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons… …both end with full orbitalsF F8 Valenceelectrons
  • 20. 20A Single Covalent Bond is... A sharing of two valence electrons. Only nonmetals and hydrogen formcovalent bonds. Different from an ionic bondbecause they actually formmolecules. H - H
  • 21. 21Multiple Bonds Sometimes atoms share more thanone pair of valence electrons. A double bond is when atoms sharetwo pairs of electrons O = O A triple bond is when atoms sharethree pairs of electrons (6 total) N NWhat’s the dealwith the oxygendot diagram?
  • 22. 22Bond Strength The shorter the bond the stronger thebond–Triple bond > double bond > singlebond
  • 23. 23Types of Covalent Bonds A covalent bond in which the bondingelectrons in the molecular orbital areshared equally is a nonpolar covalentbond. A covalent bond in which the bondingelectrons in the molecular orbital areshared unequally is a polar covalentbond.
  • 24. 24
  • 25. 25Ionic Compounds vs. Covalent CompoundsIoniccompoundsThe Union of a metaland nonmetalTransferredElectrostaticStrongSolidHighGoodSubjectDefinitionHow are the electronsarrangedForces that hold thebond togetherStrength of Bonds(weak or strong)State of matter @ roomtempertureMelting Point & BoilingPointConductionCovalentcompoundsThe union of two or morenonmetals/metalloidSharedElectrostaticWeakGas or LiquidLowPoor