(40) GCSE Chemistry Revision "Covalent Bonding 1: Bonding in Hydrogen, Chlorine and Hydrogen chloride"

Covalent Bonding Overview

• Covalent bonding occurs when non-metal atoms bond together by sharing electrons.

• Important to differentiate from ionic bonding, which occurs between metals and non-metals.

Key Concepts of Covalent Bonding

Definition of Covalent Bonding

• Covalent bonding involves non-metal atoms sharing electron pairs to achieve a full outer electron shell.

Simple Covalent Molecules

• Molecule Example: Hydrogen (H₂)

  • Two hydrogen atoms bond to form H₂.

  • Each hydrogen atom has one electron, requiring one more to fill its outer shell.

  • Bonding Process:

    • Overlap of energy levels to share electrons.

    • Results in a full outer energy level, mimicking stable noble gas configuration.

Representations of Covalent Bonds

• Energy Level Diagram: Shows the energy levels of each atom and the overlap during bonding.

• Dot and Cross Diagram:

  • Uses dots and crosses to represent shared and unshared electrons of outer energy levels.

  • For H₂: Shared electron pairs shown clearly.

• Stick Diagram: Simplified representation using a line to show the covalent bond (shared pair of electrons).

More Complex Covalent Molecules

Chlorine Molecule (Cl₂)

• Two chlorine atoms (each with 17 electrons, 7 in the outer level from group 7).

• Requires one additional electron for each atom to fill the outer shell.

  • Formed by overlapping energy levels, resulting in a shared pair of electrons.

• Representations include:

  • Energy level diagram for Cl₂.

  • Dot and cross diagram for Cl₂ to illustrate shared electrons.

  • Stick diagram indicating the single covalent bond.

Hydrogen Chloride (HCl)

• Hydrogen (1 electron) and Chlorine (7 electrons) bond together.

• Both atoms require one extra electron to achieve a full outer shell.

• Bonding process involves:

  • Overlapping outer energy levels to share electrons.

• Representations include:

  • Dot and cross diagram for HCl.

  • Stick diagram demonstrating the bond.

Exam Preparation Tips

• Be prepared to draw energy level diagrams, dot and cross diagrams, and stick diagrams for covalent molecules.

• Practice with questions from the revision workbook related to covalent bonding.