Properties of Compounds - Ionic, Covalent and Metallic


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Properties of Compounds - Ionic, Covalent and Metallic

  1. 1. Recap, we have learnt <ul><li>2 types of bonds exist between compounds </li></ul><ul><li>Covalent Bonds </li></ul><ul><li>- Electrons are shared </li></ul><ul><li>Ionic Bonds </li></ul><ul><li>- Electrons are Transferred </li></ul>- Balancing charges
  2. 2. <ul><li>(D) Properties of Ionic Compounds: </li></ul><ul><li>made of crystals </li></ul><ul><li>have high melting points </li></ul><ul><li>often soluble in water </li></ul><ul><li>conduct electricity in water </li></ul>
  3. 3. They are crystalline solids 2D Image
  4. 4. Why do ionic compounds have high melting points? Opposite charges attract , forming strong ionic bonds . Thus a lot of energy is needed to separate the ions.
  5. 5. Why do ionic compounds dissolve in water? The electrons in H 2 O molecule are not evenly spread. One end of the molecule is slightly negative compared to the other end.
  6. 6. <ul><li>The water molecules are attracted to the ions and pull them from the giant structure. </li></ul><ul><li>The compound dissolves. </li></ul><ul><li>Its ions are now free to move around  able to conduct electricity. </li></ul>
  7. 7. <ul><li>Electrical Conductivity: </li></ul><ul><li>Ionic compounds when solid do not conduct electricity . </li></ul><ul><li>The ions are tightly held in place in the lattice structure and are unable to carry charges. </li></ul><ul><li>However, when molten or dissolved in water , they can conduct electricity because the crystal lattice has broken down and the ions can move . </li></ul>Do covalent compounds dissolve and conduct electricity too?
  8. 8. <ul><li>(D) Metallic Bonding </li></ul><ul><li>Metals generally have the following properties: </li></ul><ul><li>High melting and boiling points </li></ul><ul><li>Conduct electricity and heat </li></ul><ul><li>Hard and dense </li></ul><ul><li>Can be hammered into shapes ( malleable ) </li></ul><ul><li>Can be drawn out into wires ( ductile ) </li></ul>
  9. 9. Metal atoms (or ions) are held together by a sea of electrons. Each metal atom gives up electrons from its outer shell into the sea or cloud of electrons .
  10. 10. These free electrons explain how electricity can pass through solid metals.
  11. 11. Lets Compare the 3 types of compounds – Covalent, Ionic & Metallic <ul><li>Watch the video and answer these questions </li></ul><ul><li>Covalent Compound </li></ul><ul><li>= Naphthalene </li></ul><ul><li>Ionic Compound </li></ul><ul><li>= NaCl </li></ul><ul><li>Metallic Compound </li></ul><ul><li>= Tin </li></ul>
  12. 12. Questions : Copy these onto your notes <ul><li>Which substance conducts electricity when solid? </li></ul><ul><li>Which substance conducts when dissolved in water? </li></ul><ul><li>Which substance does not dissolve in water? </li></ul>
  13. 13. Summary <ul><li>Today we have touched on </li></ul><ul><li>The properties of ionic compounds </li></ul><ul><li>Metallic bonding (sea of electrons) </li></ul><ul><li>Some differences between the 3 types of compounds. </li></ul>