Properties of Molecular Substances & Covalent Structures

• What type of bond do non-metals form by sharing electrons?

  Covalent bonds
• What is the result of non-metals joining by covalent bonds?

  Atoms have full outer shells
• What are small molecules formed by non-metals called?

  Simple molecular substances
• What is a key property of covalent bonds?

  They are very strong
• What must happen to break covalent bonds in giant structures?

  A lot of energy is needed
• What happens to intermolecular forces when comparing chlorine, bromine, and iodine?

  More intermolecular forces exist as size increases
• At what temperature does chlorine boil?

  -34 degrees Celsius
• Why do simple molecular substances have low melting and boiling points?

  Weak intermolecular forces need to be broken
• What is the boiling point of bromine?

  59 degrees Celsius
• What is the boiling point of iodine?

  184 degrees Celsius
• Why can't simple molecular substances conduct electricity?

  They have no free electrons
• What are giant covalent structures made of?

  Huge numbers of non-metal atoms
• How are atoms arranged in giant covalent structures?

  In regular repeating lattices
• What is a key property of giant covalent structures?

  They have high melting and boiling points
• Why do giant covalent structures not conduct electricity?

  They don't contain charged particles
• What is the exception to the conductivity rule among giant covalent structures?

  Graphite conducts electricity
• What is silicon dioxide also known as?

  Silica
• What is the ratio of silicon to oxygen atoms in silicon dioxide?

  1 to 2
• What is the main component of sand?

  Silicon dioxide
• What are the differences between simple molecular substances and giant covalent structures?

  • Simple molecular substances:
  • Small molecules
  • Weak intermolecular forces
  • Low melting and boiling points
  • Do not conduct electricity

  
  

  • Giant covalent structures:
  • Large networks of atoms
  • Strong covalent bonds
  • High melting and boiling points
  • Generally do not conduct electricity (except graphite)
• What are the key takeaways about covalent bonding in non-metals?

  • Non-metals form covalent bonds by sharing electrons.
  • Simple molecular substances consist of few atoms.
  • Giant covalent structures consist of many atoms in a lattice.
  • Properties differ significantly between simple and giant structures.