Giant Covalent Substances

• Millions atoms join covalent bonds in substances such as sand, diamond, and graphite.

  Covalent bond in these substance do for form molecules but vast networks of atom called Giant Covalent Structures.
• Giant Covalent Structure have very high melting and boiling point and are very hard
• Sand is a Giant Covalent Structure;

  • Made of mineral quartz
  • Has a giant covalent structure made of silicon and oxygen atoms
  • Each silicon atom is bonded to 4 oxygen atom and each oxygen is bonded with 2 silicon atoms.

  
• Allotopes are different forms of the same element; like diamond and graphite are both made up of carbon atoms.
• Structure of Diamond:

  • A carbon atom forms covalent bond with 4 others, Each outer atoms them bonds to four more and so on
  • Eventually billions of carbon atoms are bonded together in a Giant covalent structure.
  • Result in a single crystal of diamond.

  
• Properties of diamond:

  • Very hard
  • High melting and boiling point - a lot of energy is needed to break the strong covalent bonds
  • Cannot conduct electricity due to no free electron or ion to carry the charges
• Structure of Graphite:

  • Each carbon atom forms covalent bonds with 3 others giving a ring of six atoms
  • The ring form a flat sheet lie on top of each other, held together by weak forces ( London forces)

  
• Properties of Graphite:

  • Only three of the four electrons in the outer shell
  • Soft and slippery-layer can easily slide over each other
  • Weak forces of attraction which is easy to break meaning less energy needed
  • Graphite does conduct electricity-the only non-metal to do so. Each layer has a delocalize electron, allowing it to carry charge.