GCSE Combined Science (AQA)

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Properties of Small Molecules

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Bonding, structure, and the properties of matter Chemical bonds, ionic, covalent and metallic

Properties of Small Molecules

5:03 Covalent Bonding and Simple Covalent Structure Properties
Spec 4.2.1.4 4.2.2.1 4.2.2.4
Previous Covalent Bonding Diagrams Next Limitations of Covalent Bonding Models
  • Small molecules have a simple covalent structure.
  • Examples include hydrogen (H2), ammonia (NH3), and carbon dioxide (CO2).
  • Ball and stick models represent these molecules, showing covalent bonds.
  • Small molecules have a fixed number of atoms; e.g., CO2 is always CO2.
  • Many substances, like water (H2O), are made up of small molecules.
  • Water consists of two hydrogen atoms bonded to an oxygen atom.
  • A glass of water contains approximately 6.7 septillion molecules.
  • Strong covalent bonds exist between atoms in a molecule.
  • Weak intermolecular forces exist between molecules.
  • Melting or boiling involves overcoming weak intermolecular forces.
  • Covalent bonds within molecules remain intact during phase changes.
  • Substances with small molecules have low melting and boiling points.
  • Water has a melting point of 0��C and a boiling point of 100��C.
  • Small molecules are often liquids or gases at room temperature.
  • Larger molecules have stronger intermolecular forces and higher melting/boiling points.
  • Bromine (Br2) and iodine (I2) illustrate size-related boiling point differences.
  • Small molecules do not conduct electricity due to lack of overall electric charge.
  • Neutral molecules, like oxygen, do not allow charge flow, preventing electrical conduction.

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