Properties of Small Covalent Molecules

• Why do small covalent molecules have low melting and boiling points?

  They have weak intermolecular forces
• What state are small covalent molecules usually in at room temperature?

  Gases or liquids
• What is the boiling point of water?

  100° C
• Why is hydrogen used to illustrate the properties of small covalent molecules?

  It is a liquid at very cold temperatures
• What happens to the vibration of molecules as temperature increases?

  It increases until intermolecular forces break
• What are intermolecular forces?

  Weak forces between molecules
• What is required to turn small covalent molecules from liquid to gas?

  Energy to break weak intermolecular forces
• What happens to covalent bonds when a substance melts or boils?

  They are not broken
• How do intermolecular forces change with larger alkane molecules?

  They increase, requiring more energy to break
• Why do small covalent molecules not conduct electricity?

  They do not have an overall electric charge
• What is a common exam question regarding small covalent molecules?

  Why they do not conduct electricity
• What are the key properties of small covalent molecules?

  • Low melting and boiling points
  • Usually gases or liquids at room temperature
  • Do not conduct electricity
• What is the relationship between the size of alkane molecules and their boiling points?

  • Larger alkane molecules have higher boiling points
  • Increased size leads to stronger intermolecular forces
  • More energy is required to break these forces