Free Science Lessons: Covalent Bonding

Introduction

• Focus: Understanding how electrons are shared in covalent bonding.
• Objective: Learn to draw diagrams for covalent bonding in water, ammonia, and methane.

Recap of Covalent Bonding

• Occurs between non-metal elements.
• Covalent bond = shared pair of electrons.
• Strong bonds.
• Examples from previous lesson:
  • Hydrogen
  • Chlorine
  • Hydrogen chloride

Molecules with Several Atoms

• Focus on water (H2O), ammonia (NH3), and methane (CH4).

Water (H2O) Molecule

• Composition: 2 hydrogen atoms, 1 oxygen atom.
• Oxygen Atom:
  • 8 electrons total.
  • 2 electrons in the first energy level.
  • 6 electrons in the outer energy level (only outer level involves in bonding).
• Hydrogen Atoms:
  • 1 electron each.
• Bonding:
  • Requires overlapping of outer energy levels.
  • Each hydrogen atom shares one electron with oxygen.
  • Forms two covalent bonds.
• Diagrams:
  • Energy level diagram.
  • Dot and cross diagram.
  • Stick diagram (line represents a single bond).

Ammonia (NH3) Molecule

• Composition: 1 nitrogen atom, 3 hydrogen atoms.
• Nitrogen Atom:
  • 5 electrons in the outer energy level.
• Hydrogen Atoms:
  • 1 electron each.
• Bonding:
  • Nitrogen shares electrons with each hydrogen to form three covalent bonds.
• Diagrams:
  • Energy level diagram.
  • Dot and cross diagram.
  • Stick diagram.

Methane (CH4) Molecule

• Composition: 1 carbon atom, 4 hydrogen atoms.
• Carbon Atom:
  • 4 electrons in the outer energy level.
• Hydrogen Atoms:
  • 1 electron each.
• Bonding:
  • Carbon shares electrons with four hydrogen atoms to form four covalent bonds.
• Diagrams:
  • Energy level diagram.
  • Dot and cross diagram.
  • Stick diagram.

Additional Resources

• Questions on covalent bonding available in the revision workbook.