Covalent Bonding Lesson - GCSE Chemistry AQA Higher Triple

1. Structure and Formation of Covalent Bonds

• Covalent Bonds Definition: A type of chemical bond where pairs of electrons are shared between atoms.
• Purpose: Covalent bonds aim to achieve a full outer shell of electrons, making atoms more stable.
• Formation: Typically occurs between non-metal atoms.
• Examples: Hydrogen molecule (H2), Water (H2O), Methane (CH4).

2. Representation of Covalent Bonds

• Dot and Cross Diagrams: Used to show the sharing of electron pairs between atoms.
  • Dots and crosses represent electrons from different atoms.
• Structural Formulas: Uses lines to represent shared electron pairs.
  • Example: H-H for H2, O=O for O2.
• Displayed Formulas: Shows all the atoms and bonds in a molecule.

3. Types of Covalent Structures

• Simple Molecular Substances:
  • Small molecules with strong covalent bonds within them but weak intermolecular forces.
  • Low melting and boiling points, e.g., Water (H2O), Carbon dioxide (CO2).
• Giant Covalent Structures:
  • Large networks of atoms bonded together with strong covalent bonds.
  • High melting and boiling points, e.g., Diamond, Graphite, Silicon dioxide (SiO2).

Summary

• Covalent bonding involves the sharing of electron pairs between atoms to achieve stability.
• Different methods to represent covalent bonds include dot and cross diagrams, structural, and displayed formulas.
• Covalent structures can be simple molecular or giant structures, each with distinct properties.