Ap Chapter 10 Bonding Ii

1,274 views

Published on

PP for class notes

Published in: Technology, Education
  • Be the first to comment

Ap Chapter 10 Bonding Ii

  1. 1. <ul><li>Bonding II </li></ul>
  2. 2. Bonding I – you learned.. <ul><li>Classifying Bonds </li></ul><ul><li>Calculate the Lattice Energy of Ionic Compounds </li></ul><ul><li>Write Lewis Structures </li></ul><ul><li>Formal Charges </li></ul><ul><li>Drawing Resonance Structures </li></ul><ul><li>Exceptions to the Octet Rule </li></ul><ul><ul><li>The incomplete octet </li></ul></ul><ul><ul><li>Odd-electron molecules </li></ul></ul><ul><ul><li>The expanded octet </li></ul></ul><ul><li>Using Bond enthalpies to Estimate the Enthalpy of a Reaction </li></ul>
  3. 3. Bonding II – you will learn… <ul><li>Molecular Geometry – VSEPR models </li></ul><ul><ul><li>Molecule in which the central atom has NO lone pairs </li></ul></ul><ul><ul><li>Molecule in which the central atom has lone pairs </li></ul></ul><ul><ul><li>Molecule in which there is more than one central atom </li></ul></ul><ul><li>Predicting Dipole Moments </li></ul><ul><li>Hybridization of Atomic Orbitals </li></ul><ul><ul><li>Hybridization of s and p orbitals </li></ul></ul><ul><ul><li>Hybridization of s, p and d orbitals </li></ul></ul><ul><ul><li>Hybridization in molecules containing double and triple bonds. </li></ul></ul><ul><li>Molecular Orbital Diagrams </li></ul>
  4. 4. Molecular Geometry - VSEPR models <ul><li>VSEPR models - Accounts for electron pairs around atoms. </li></ul><ul><ul><li>Minimizes electron-pair repulsion. </li></ul></ul><ul><li>Guidelines for Applying </li></ul><ul><ul><li>Draw the Lewis Structures </li></ul></ul><ul><ul><li>Only consider electrons around the central atom </li></ul></ul><ul><ul><ul><li>Account for both bonding and non-bonding (lone) pairs </li></ul></ul></ul><ul><ul><ul><li>Treat double and triple bonds as single bonds, Ex: CO 2 .. O=C=O. </li></ul></ul></ul><ul><ul><li>Look at table 10.1 for overall arrangement of electrons. </li></ul></ul><ul><ul><li>In predicting bond angles </li></ul></ul><ul><ul><ul><li>Lone pairs repel lone pairs and shared pairs more strongly than bond pairs of electrons. </li></ul></ul></ul><ul><ul><ul><li>There is no accurate way to predict exact bond angles when the central atom possesses one or more lone pairs. </li></ul></ul></ul>
  5. 5. Molecular Geometry - atom has NO lone pairs <ul><li>General formula AB x where A is the central atom, B is/are the surrounding atoms and x is a number between 2 and 6…… most of the time. </li></ul><ul><li>Table 10.1 shows five possible arrangements of electron pairs around the central atom A . </li></ul><ul><ul><li>Table 10.1 shows number of electron pairs, arrangement and molecular geometry. </li></ul></ul><ul><ul><li>Predict the geometry of CO 2 , SnCl 4 and NO 3 -1 , PF 5 </li></ul></ul><ul><li>Problems 10.8, 10.10, 10.12 </li></ul>
  6. 6. Molecular Geometry – atom has lone pairs <ul><li>General formula AB x E y where A is the central atom, B is/are the surrounding atoms, E is the number of lone pairs and x is a number between 2, 3.. and y 1,2,3, …... </li></ul><ul><li>Approach.. </li></ul><ul><ul><li>Count all electron pairs on the central atom </li></ul></ul><ul><ul><li>The number of electron pairs around the central atom determines the electron arrangement around the central atom </li></ul></ul><ul><ul><li>HOWEVER, the molecular geometry will NOT be the same as the electron arrangement. Geometry is based on atoms alignment, leaving out the lone pairs. </li></ul></ul><ul><li>Table 10.2 – lone pair configuration </li></ul><ul><ul><li>Class of molecule, i.e. AB x E y </li></ul></ul><ul><ul><li># of electron pairs </li></ul></ul><ul><ul><li>Number of bonding pairs </li></ul></ul><ul><ul><li>Arrangement </li></ul></ul><ul><ul><li>Number of lone pairs </li></ul></ul><ul><ul><li>Molecular geometry. </li></ul></ul><ul><li>Practice - Predict the geometry of O 3 , XeF 2 , IF 5 </li></ul><ul><li>Problems 10.14 </li></ul>
  7. 7. Molecular Geometry - more than one central atom <ul><li>A Central Atom </li></ul><ul><ul><li>Bonded to two or more atoms </li></ul></ul><ul><li>Many molecules have more than one central atom. </li></ul><ul><li>Solve by making each of the central atoms the central atom. </li></ul><ul><ul><li>Multi-step determination </li></ul></ul><ul><ul><li>C 2 H 8 and C 2 H 4 are examples </li></ul></ul><ul><ul><ul><li>H 4 C-CH 4 </li></ul></ul></ul><ul><ul><ul><li>H 2 C=CH 2 </li></ul></ul></ul>
  8. 8. Predicting Dipole Moments <ul><li>Two factors determine the if a molecule has a dipole moment. </li></ul><ul><ul><li>Are the bonds in the molecule polar ? </li></ul></ul><ul><ul><ul><li>Electron negativity determine if the bonds are polar. </li></ul></ul></ul><ul><ul><ul><li>Shift in electron density is symbolized by </li></ul></ul></ul><ul><ul><li>Is the molecule polar? </li></ul></ul><ul><ul><ul><li>Bond moment is a vector quantity and magnitude and direction. </li></ul></ul></ul><ul><ul><ul><li>Vector is the sum of the bond moment. </li></ul></ul></ul><ul><ul><ul><li>Check out the following; CO 2 CCl 4 , CCl 2 H 2 </li></ul></ul></ul><ul><li>Problems 10.20, 10.22, 10.24 </li></ul>
  9. 9. Valence Bond Theory (VB) <ul><li>Introduced to explain chemical bond formation. </li></ul><ul><li>Describes covalent bonding as overlapping atomic orbitals </li></ul><ul><li>Orbitals share common regions of space. </li></ul><ul><li>VB uses the concept of hybridization </li></ul><ul><ul><li>Blending/combining of two or more non-equal atomic orbits such as s and p to make a new hybrid sp orbit. </li></ul></ul><ul><ul><li>Hybrid orbitals overlap to create a covalent bond. </li></ul></ul><ul><ul><li>Hybrid orbitals allow paired electrons to become unpaired for bonding </li></ul></ul><ul><ul><ul><li>Unpaired valence electrons do the bonding. </li></ul></ul></ul><ul><li>Steps for determining type of hybrid orbitals </li></ul><ul><ul><li>Draw Lewis structures </li></ul></ul><ul><ul><li>Use VSPRE to determine electron pair arrangement (Table 10.1, 10.2) </li></ul></ul><ul><ul><li>Use Table 10.4 to determine hybrid state of central atom. </li></ul></ul>
  10. 10. Valence Bond Theory – sp hybridization <ul><li>sp hybrid orbit </li></ul><ul><ul><li>Combines the s orbital and one p-orbital to form two equal obitals called sp-orbital, i.e. BeCl 2 </li></ul></ul><ul><ul><li>Linear </li></ul></ul><ul><li>sp 2 hybrid orbit </li></ul><ul><ul><li>Combines the s orbital and two p-orbital to form two equal obitals called sp-orbital, i.e. BCl 3 </li></ul></ul><ul><ul><li>Trigonal planar – 120 o angles </li></ul></ul><ul><li>sp 3 hybrid orbit </li></ul><ul><ul><li>Combines the s orbital and three p-orbital to form two equal obitals called sp-orbital, i.e. CH 4 </li></ul></ul><ul><ul><li>Tetrahedron – 109.5 o </li></ul></ul><ul><li>Problems 10.32, 10.34, 10.36 </li></ul>
  11. 11. Valence Bond Theory – sp hybridization <ul><li>sp 3 d hybrid orbit </li></ul><ul><ul><li>5 equivalent hybrid orbitals </li></ul></ul><ul><ul><li>Trigonal bipyramid, 120 o , 90 o </li></ul></ul><ul><li>sp 3 d 2 hybrid orbit </li></ul><ul><ul><li>6 equivalent hybrid orbitals </li></ul></ul><ul><ul><li>octahedral, 90 o </li></ul></ul>
  12. 12. Hybrid double and triple bonds <ul><li>Determine the bonds that overlap with double and triple bonds </li></ul><ul><li>Two types of bonds </li></ul><ul><ul><li>Sigma σ bond – end-to-end overlap </li></ul></ul><ul><ul><li>Pi bonds – side-to-side overlap </li></ul></ul>

×