diamond and silicon dioxide

• What is the structure of giant covalent substances?

  They contain millions of covalent bonds
• How do the properties of giant covalent substances relate to their structure?

  High melting and boiling points due to strong bonds
• What type of forces exist between small covalent molecules?

  Weak intermolecular forces
• Why do small covalent substances have low melting and boiling points?

  Weak intermolecular forces require little energy to break
• What state are giant covalent substances in at room temperature?

  Solids
• Why do giant covalent substances have high melting and boiling points?

  They require a lot of energy to break strong bonds
• What element is diamond formed from?

  Carbon
• How many electrons are in the outer energy level of a carbon atom?

  Four electrons
• How does a carbon atom achieve a full outer energy level?

  By forming covalent bonds with four other carbon atoms
• Why is diamond considered an extremely hard substance?

  It has millions of carbon atoms joined by bonds
• What is the melting point of diamond?

  Over 3,700 °C
• Why can't diamond conduct electricity?

  All outer electrons are in covalent bonds
• What is silicon dioxide also known as?

  Silica
• What elements are contained in silicon dioxide?

  Silicon and oxygen
• How does silicon dioxide compare to diamond in terms of melting and boiling points?

  Both have very high melting and boiling points
• Why does silicon dioxide require a lot of energy to melt?

  It has a huge number of strong covalent bonds
• What are the properties of giant covalent substances?

  • Always solids at room temperature
  • High melting and boiling points
  • Require a lot of energy to break bonds
• What are the properties of small covalent substances?

  • Gases at room temperature
  • Low melting and boiling points
  • Weak intermolecular forces
• What is the difference between small and giant covalent substances?

  • Small covalent: few bonds, weak forces
  • Giant covalent: millions of bonds, strong forces