Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Models of chemical bonding

779 views

Published on

Published in: Education
  • Be the first to comment

  • Be the first to like this

Models of chemical bonding

  1. 1. Models of Chemical Bonding
  2. 2. Bonding in Molecules Ionic Bonds Polar Covalent Bonds Non-Polar Covalent Bonds
  3. 3. Definitions <ul><li>ELECTRONEGATIVITY is the attraction an atom has for electrons in a chemical bond. </li></ul><ul><li>A POLAR BOND is one between atoms with different electronegativities - one atom attracts electrons more strongly than the other. As a result, one atom acquires a partial positive charge and the other a partial negative charge. </li></ul>Slide
  4. 4. More Definitions <ul><li>A DIPOLE is a separation of charge. A polar bond is an example of a dipole. </li></ul><ul><li>A DIPOLE MOMENT is the magnitude of a dipole - it depends on the size of the charges involved. </li></ul><ul><li>A POLAR MOLECULE is one that possesses an overall dipole moment. </li></ul>Slide
  5. 5. Classifying Chemical Bonds <ul><li>IONIC bonds are characterized as… </li></ul><ul><ul><li>bonds between metals and non-metals </li></ul></ul><ul><ul><li>bonds between cations and anions </li></ul></ul><ul><ul><li>bonds involving a transfer of electrons (from a metal to a non-metal) </li></ul></ul><ul><li>The best classification of an ionic bond uses the concept of electronegativity . </li></ul>Slide
  6. 6. Classifying Chemical Bonds <ul><li>An ionic bond forms between two atoms with a large difference in electronegativity - usually stated as being greater than about 1.7 Paulings. </li></ul><ul><ul><li>e.g. NaCl: difference is 2.0 Paulings </li></ul></ul><ul><ul><li>e.g. CuO: difference is 1.7 Paulings </li></ul></ul>Slide
  7. 7. Classifying Chemical Bonds <ul><li>COVALENT bonds are usually described as… </li></ul><ul><ul><li>bonds between two non-metal atoms </li></ul></ul><ul><ul><li>bonds involving a sharing of electrons </li></ul></ul><ul><li>Using the concept of electronegativity, we can see that there are two types of covalent bonds. </li></ul>Slide
  8. 8. Classifying Chemical Bonds <ul><li>POLAR COVALENT BONDS result from unequal sharing of electrons by atoms that creates a small dipole. </li></ul><ul><li>This type of bond occurs when there is a small but significant difference in electronegativity - between 0.4 and 1.7 Paulings. </li></ul><ul><ul><li>e.g. N-H: diff is 0.9 Paulings </li></ul></ul><ul><ul><li>e.g. Cu-S: diff is 0.7 Paulings </li></ul></ul>Slide
  9. 9. Slide Classifying Chemical Bonds <ul><li>NON-POLAR COVALENT BONDS result from an equal sharing of electrons. </li></ul><ul><li>There is no dipole created since the electrons are shared equally. </li></ul><ul><li>This bond forms between atoms with similar (or the same) electronegativities - differences between 0 and 0.4 Paulings. </li></ul>
  10. 10. Slide Exercise <ul><li>Classify the following chemical bonds. Show your work. </li></ul><ul><ul><li>Li-F </li></ul></ul><ul><ul><li>Br-Br </li></ul></ul><ul><ul><li>Fe-O </li></ul></ul><ul><ul><li>Al-Cl </li></ul></ul><ul><ul><li>C-S </li></ul></ul><ul><ul><li>C-H </li></ul></ul>
  11. 11. Slide Polarity of Molecules <ul><li>A diatomic molecule (e.g. HF) will be polar if its bond is polar. </li></ul><ul><li>Larger molecules are polar only when the following criteria are met: </li></ul><ul><ul><li>they possess at least one polar bond </li></ul></ul><ul><ul><li>their geometries do not result in the dipoles cancelling each other out! (e.g. CO 2 ) </li></ul></ul>

×