Metallic Bonding

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Metallic Bonding

  1. 1. Metallic Bonding <ul><li>Bonding of metal atoms to metal atoms </li></ul><ul><li>Metals lose valence electrons to become Positive ions </li></ul><ul><ul><li>Positive ions vibrate about a fixed position </li></ul></ul><ul><ul><li>Lost electrons free to move around +ve ions </li></ul></ul><ul><li>Holds together to form </li></ul><ul><ul><li>Metallic Lattice </li></ul></ul>
  2. 2. Metallic Bonding <ul><li>Metallic bonding is usually described by the electron-sea model </li></ul><ul><li>the valence electrons of the metal’s atoms are spread out through the lattice of the metal </li></ul>
  3. 3. Metallic Bonding <ul><li>Essentially all the valence electrons belong to all the atoms in the substance </li></ul>
  4. 4. Metal properties <ul><li>Metals are </li></ul><ul><li>Conductors of electricity </li></ul><ul><li>Conductors of heat </li></ul><ul><li>Malleable </li></ul><ul><li>Ductile </li></ul><ul><li>Lustrous </li></ul><ul><li>High melting point </li></ul><ul><li>High boiling point </li></ul><ul><li>Metallic bonding can explain all of these properties </li></ul>
  5. 5. Conduction <ul><li>The sea of electrons explains why metals are good thermal and electrical conductors </li></ul><ul><li>the mobile electrons in the electron sea are excellent charge carriers </li></ul>+ + + + + + + + + + + +
  6. 6. Conduction of heat <ul><li>Also the ions vibrate more freely than other (primary) bonds which means it is easier for each atom to transmit thermal energy to their neighbour </li></ul><ul><li>The regular repeating lattice and close proximity of the ions promotes the transfer of energy. </li></ul>
  7. 7. Malleability and Ductility <ul><li>Metals are malleable: </li></ul><ul><ul><li>Hammered into shape (bendy). </li></ul></ul><ul><li>Metals are ductile </li></ul><ul><ul><li>drawn into wires </li></ul></ul><ul><li>How does this picture illustrate malleability? </li></ul>
  8. 8. Malleable + + + + + + + + + + + +
  9. 9. Malleable <ul><li>Electrons allow atoms to slide by. </li></ul>+ + + + + + + + + + + +
  10. 10. Ductile + + + + + + + + + + + +
  11. 11. Ductile The atoms can slip past each other into a long chain as the electrons move between them + + + + + + + + + + + +
  12. 12. Lustrous <ul><li>Metals are lustrous that is they generally have a shiny appearance </li></ul><ul><li>Rows of atoms – all the same </li></ul><ul><li>Perfectly lined up – in crystal lattice </li></ul><ul><li>Light can’t get through regular lattice </li></ul><ul><li>Light is reflected – lustrous </li></ul><ul><li>Sea of electrons on surface of the metals contributes to this lustre. </li></ul>
  13. 13. Melting and boiling points <ul><li>Metals have a (continuous) lattice </li></ul><ul><li>Charged ions strongly bound to electrons by electrostatic attraction between unlike charges </li></ul><ul><li>Lots of energy needed to separate </li></ul><ul><li>High melting & boiling points </li></ul>+ e - e - e - e - e -

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