Properties of Giant Covalent Structures (Oxford AQA IGCSE Combined Science Double Award)

Melting & Boiling Points of Giant Covalent Structures

• Covalent bonding can be responsible for substances that have many different structures and therefore different physical properties

• We have already seen how simple molecules such as H₂O and N₂ form covalently bonded molecules with a fixed number of atoms

• Some covalent structures have a huge number of non-metal atoms bonded to other non-metal atoms via strong covalent bonds

  • They are called giant structures or macromolecules

• Examples include diamond, graphite and silicon dioxide

  • Diamond and graphite are made from carbon atoms 

  • Silicon dioxide (silica) is made from silicon and oxygen atoms

• All giant covalent structures have high melting points because:

  • There are strong covalent bonds between atoms

  • These require lots of energy to overcome 

Giant covalent structures