.4 covalent bonding

• When atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong
• Covalently bonded substances may consist of small molecules.
• Some covalently bonded substances have very large molecules, such as polymers.
• Some covalently bonded substances have giant covalent structures, such as diamond and silicon dioxide
• The covalent bonds in molecules and giant structures, 


  can be represented in the following forms:

  
• Polymers can be represented in the form: