Bonding Notes Page |1 Unit 5b: Bonding and Shape (Link to Prentice Hall Text: Chapters 15 & 16) Date Due Assignments Page Number: Problem Numbers Assignment 1: Ionic Bonding 432: 23, 25, 26, 44 470: 53 Assignment 2: Covalent Lewis Structures 470: 30, 32, 33, 37, 38, 41 Assignment 3: Molecular Geometry, Sigma + Pi 470: 47, 48, 63 Assignment 4: Hybridization 470: 50, 66 Assignment 5: Polarity 470: 52, 54 Assignment 6: Coordinate Covalent Bonds 470: 34 Assignment 7: Metallic Bonding 432: 39 Assignment 8: Intermolecular Forces 470: 55, 56, 57, 58 Bonding Notes Page |2 A. What is a Chemical Bond? The Nature of the Chemical Bond A chemical bond is best described as an ____________________________________________________. Chemical bonds are created due to forces between ______________ and ________________ within an atom. ____________________________to break a chemical bonds, ______________. It is an _____________________________ process. When a chemical bond forms,________________________________________. It is an _____________________________ process. B. Valence Dot Structures for Atoms Valence Number Periodicity Group Period 2 Ion 3 Ion 1 2 13 15 16 17 Bonding Notes Page |3 C. Properties of Ionic Compounds Ionic Dot Structures 1. Why do metals tend to lose electrons and non-metals tend to gain electrons? Metals: ________________________________________________________ Non-metals:____________________________________________________ 2. What electron configuration does each atom attain in an ionic compound? Each atom attains the electron configuration of a ______________________ Ionic Dot Structures When writing Lewis Diagrams for ionic compounds, simply show the Lewis Dot Structure for each individual ion (include charge), and put the atoms in brackets. Draw the Lewis Diagram for each of the following ionic compounds. 1. NaCl Name: 2. LiF 3. CaO Name: 4. MgS Name: 5. MgCl2 Name: 6. CaI2 Name: 7. RbBr Name: 8. SrF2 Name: Name: Bonding Notes Page |4 Lewis Diagrams for Covalent Compounds The bonds for covalent compounds do not involve the transfer of electrons. Covalent compounds involve the sharing of electrons. Vocab Lone pairSingle covalent bondDouble covalent bondTriple covalent bond- Resonance- General Guidelines for Drawing Lewis Diagrams for Covalent Compounds Step 1: Count the total number of valence electrons. Step 2: Assemble the bonding framework (skeleton). Place the most electronegative element in the center. Step 3: Arrange the remaining electrons so that each atom has 8 electrons around it (the octet rule). If necessary, place additional pairs of electrons between the atoms to form additional bonds. Step 4: Check for exceptions to the octet rule. Step 5: Evaluate whether the formal charges (FC) on the atoms are reasonable. Step 6: If necessary, draw resonance structures. Formal Charge = Drawing Lewis Structures with Simple Single, Double and Triple Bonds Use the rules above to draw Lewis structures for the following compounds. 1. CH4 Molecular Geometry:___________________ 2. H2S Molecular Geometry:___________________ Bonding Notes 3. PH3 Molecular Geometry:___________________ 5. H2O Molecular Geometry:___________________ 7. C2H4 Molecular Geometry:___________________ 9. CH3Br Molecular Geometry:___________________ 11. C2H3Cl Molecular Geometry:___________________ Page |5 4. NH3 Molecular Geometry:___________________ 6. SF4 Molecular Geometry:___________________ 8. OH- Molecular Geometry:___________________ 10. CO32- Molecular Geometry:___________________ 12. CO2 Molecular Geometry:___________________ Bonding Notes 13. SO3 Molecular Geometry:___________________ 15. XeF4 Molecular Geometry:___________________ 17. SCN- Molecular Geometry:___________________ 19. NI3 Molecular Geometry:___________________ Page |6 14. N2O Molecular Geometry:___________________ 16. NO3- Molecular Geometry:___________________ 18. C3H8 Molecular Geometry:___________________ 20. BF3 Molecular Geometry:___________________ Bonding Notes Page |7 D. Summary of Hybridization and Molecular Geometry Central Electron Pairs 2 Electron Geometry Linear Number of Bonds 2 3 Trigonal planar 2 3 Trigonal planar 3 4 Tetrahedral 2 4 Tetrahedral 3 4 Tetrahedral 4 5 Trigonal bypyramidal 2 5 Trigonal bypyramidal 3 5 Trigonal bypyramidal 4 5 Trigonal bypyramidal 5 6 octahedral 2 6 octahedral 3 6 octahedral 4 6 octahedral 5 6 octahedral 6 Bond Angles Molecular Geometry / Shape Hybridization Bonding Notes Page |8 E. Three-Dimensional Representations of Covalent Compounds The following are VSEPR (Valence Shell Electron Pair Repulsion) geometries for covalent compounds. VSEPR is based on the idea that regions of electrons (either lone pairs or bonds) will repel to seek the configuration where they are the furthest apart, and therefore the most stable. Bonding Notes F. Hybridization of Orbitals Valence Bond Theory (Linus Pauling) – In order for atoms to bond, orbitals must overlap. sp Example: BeCl2 sp2 Example: BF3 sp3 Example: CH4 Page |9 Bonding Notes P a g e | 10 G. Sigma and Pi Bonds Determining Number of Sigma and Pi Bonds Single Bonds Consist of: __________________________________________________ Double Bonds Consist of:________________________________________________ Triple Bonds Consist of:___________________________________________________ H. Bond Polarity and Molecular Polarity Determining the Polarity of a Bond If two atoms, with a bond between them, have different electronegativities, the bond is described as __________________________________________. Polar covalent bonds have an end that is partially _____________________and partially _________________________ in charge. A polar bond is said to have a ______________________ . Nonpolar covalent bonds have no charge separation. Scale: Bonding Notes P a g e | 11 Determining the Polarity of a Compound If a molecule is symmetrical, the molecule is __________________________________________. If a molecule is nonsymmetrical, the molecule is _______________________________________. Determining Molecular Polarity Draw the Lewis Structures for the following compounds and determine whether they are polar or nonpolar. Important: Place lone pairs on the same atom adjacent to each other. 1. HCl 2. CO2 3. CCl4 4. H2O 5. O2 6. C2HCl 7. HCN 8. C2H4 Bonding Notes P a g e | 12 I. J. Compounds Containing Ionic and Covalent Bonds Identifying Compounds with Ionic and Covalent Bonds Ionic compounds that contain _____________________________________ ions contain both ionic and covalent bonding. 1. Sodium nitrate 2. K3PO4 3. KNO2 4. Ammonium chloride K. Coordinate Covalent Bonds Identifying Coordinate Covalent Bonds In some cases one atom donates all of the electrons to a bond. In this case, it is called a coordinate covalent bond. Example 1: NH4+ Example 2: H3O+ Bonding Notes P a g e | 13 L. Intermolecular Forces: Influence on Vapor Pressure and Boiling Points Three Types of Intermolecular Forces Intramolecular forces: Intermolecular Forces: As forces of attraction between molecules increase, the: (1) Vapor Pressure __________________________________________________ (2) Boiling Point __________________________________________________ A. Intermolecular Force (1): Hydrogen Bonding Force - STRONGEST Occurs only between molecules that have a _________ atom bonded to a fluorine, oxygen or nitrogen atom. B. Intermolecular Force (2): Dipole-Dipole Force - INTERMEDIATE Occurs between __________________ molecules. C. Intermolecular Force (3): Dispersion (van der Waals) Force - WEAKEST Occurs between ____________________ molecules. As the mass of the molecule/atom increases, the van der Waals forces. Bonding Notes P a g e | 14 M. Distinguishing Ionic, Metallic, Molecular and Covalent Network Solids Differences in Bond Type in Various Solids Example Picture Properties Ionic Solid Metallic Solid Molecular Solid Covalent Network Solid Metals are atoms that have low ionization energies and a small number of valence electrons. The inner electrons of metal atoms are arranged in a crystalline lattice. The valence electrons move freely throughout the lattice and are not attached to any one atom in particular.