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Other Bonding

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Other Bonding

  1. 1. Other types of bonding
  2. 2. Other types of bonding <ul><li>Lesson Objectives </li></ul><ul><li>Describe metallic bonding present in a giant metallic lattice </li></ul><ul><li>Describe intermolecular forces (van der Waals’ forces), based on instantaneous and permanent dipoles </li></ul><ul><li>Describe in simple terms the giant molecular structures of graphite and diamond </li></ul><ul><li>Describe hydrogen bonding between molecules containing –OH and –NH 3 groups </li></ul>
  3. 3. Metallic Bonding <ul><li>Metals have many unique properties, they are shiny, and are good conductors of both heat and electricity. </li></ul><ul><li>They are ductile and malleable, they often have high tensile strengths and are usually hard. </li></ul>
  4. 4. <ul><li>Metal atoms are found in a metallic lattice </li></ul><ul><li>In the lattice the metal atoms are positive ions. They use their outer shell electrons. </li></ul><ul><li>These electrons have the ability to move throughout the lattice. The positive metal ions are said to be located in a ‘sea’ of electrons </li></ul>
  5. 5. <ul><li>The metallic lattice is held together by the attractive forces between the electrons and the positive metal ions. </li></ul><ul><li>The mobile electrons explain how metals can conduct electricity. </li></ul><ul><li>Vibration of the ions and electrons allow conduction of heat. </li></ul><ul><li>When the metals are physically deformed the ions can move past each other but the bonding is not broken. </li></ul>
  6. 6. Intermolecular forces <ul><li>Solid, liquid and gas states provide evidence for intermolecular forces. </li></ul><ul><li>For a gas to condense into a liquid the molecules must be attracted to each other. </li></ul><ul><li>Energy is needed to overcome this attraction when a solid melts into a liquid. </li></ul>
  7. 7. <ul><li>There are three types of instantaneous force: </li></ul><ul><li>Instantaneous dipole-induced dipole forces </li></ul><ul><li>Dipole-dipole forces </li></ul><ul><li>Hydrogen bonds </li></ul>
  8. 8. Instantaneous dipole-induced dipole forces <ul><li>Consider the electrons moving in the orbitals around atoms. They are moving fast around the whole atom. </li></ul><ul><li>At any given time the electrons may be found on only one side of the atom that would make the atom polar for a short amount of time. </li></ul>
  9. 9. <ul><li>These dipoles will cause the atom nearby to become polar causing a weak attractive force. </li></ul><ul><li>Instantaneous dipole-induced dipole forces are also known as Van der Waals’ forces. </li></ul><ul><li>The strength of the force depends upon the number of electrons and protons present </li></ul>
  10. 10. <ul><li>Low density poly(ethene) LDPE </li></ul><ul><li>High density poly(ethene) HDPE </li></ul><ul><li>Teflon </li></ul>
  11. 11. Permanent dipole-dipole forces <ul><li>Polar molecules, molecules that have a permanent electric dipole are attracted to each other. </li></ul>
  12. 12. Hydrogen Bonds <ul><li>A hydrogen bond is a strong dipole-dipole attraction between a hydrogen atom and a neighbouring negative atom eg. Oxygen or Nitrogen. </li></ul><ul><li>In water hydrogen bonds hold the water molecules together </li></ul>
  13. 13. <ul><li>Ice </li></ul><ul><li>Surface Tension </li></ul><ul><li>High boiling point </li></ul>

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