properties of small covalent molecules

• Small covalent molecules


  • Have low melting and boiling points
  • Are usually gases or liquids at room temperature
• Small covalent molecules


  • Methane
  • Other molecules shown
• Melting and boiling points of small covalent molecules

  Very low
• Water is a liquid at room temperature, but has a relatively low boiling point of 100°C
• Why small covalent molecules have low melting and boiling points

  1. Atoms in each molecule held together by strong covalent bonds

  2. Weak intermolecular forces between molecules

  3. As temperature increases, vibration of molecules increases

  4. At certain point, vibration is strong enough to break weak intermolecular forces, causing molecules to turn to gas (boil)
• As size of covalent molecule increases

  Intermolecular forces increase, requiring more energy to break
• Small covalent molecules do not conduct electricity
• Reason small covalent molecules do not conduct electricity

  They do not have an overall electric charge