(40) GCSE Chemistry Revision "Covalent Bonding 2: Bonding in Water, Ammonia and Methane"

Covalent Bonding

Definition

• Covalent Bond: A strong bond formed by the sharing of a pair of electrons between two non-metal atoms.

Key Characteristics

• Non-Metal Elements: Covalent bonds occur between non-metals.

• Electron Sharing: Involves overlapping outer energy levels of atoms to achieve full outer energy levels.

• Strong Bonds: Covalent bonds are strong due to the shared electrons.

Molecules Discussed

Water (H2O)

• Composition: 2 Hydrogen atoms and 1 Oxygen atom.

• Oxygen Atom: 8 total electrons (2 in first level, 6 in outer level).

• Hydrogen Atoms: Each has 1 electron, needing 1 more for a full outer level.

• Bonding:

  • Oxygen requires 2 electrons to complete its outer shell.

  • Hydrogen atoms provide electrons, forming 2 covalent bonds with oxygen.

• Diagrams:

  • Dot and Cross Diagram: Illustrates electron sharing.

  • Stick Diagram: Shows two lines representing two covalent bonds.

Ammonia (NH3)

• Composition: 1 Nitrogen atom and 3 Hydrogen atoms.

• Nitrogen Atom: 5 electrons in its outer energy level.

• Bonding:

  • Each Hydrogen atom contributes 1 electron leading to 3 shared pairs.

  • Result: Nitrogen completes its outer energy level via 3 covalent bonds.

• Diagrams:

  • Energy Level Diagram: Visual representation of bonding.

  • Dot and Cross Diagram: Illustrates shared electrons among the atoms.

  • Stick Diagram: Depicts three covalent bonds with three single lines.

Methane (CH4)

• Composition: 1 Carbon atom and 4 Hydrogen atoms.

• Carbon Atom: 4 electrons in its outer energy level.

• Bonding:

  • Each of the 4 Hydrogen atoms shares 1 electron with Carbon.

  • Result: Carbon achieves a full outer energy level via 4 covalent bonds.

• Diagrams:

  • Energy Level Diagram: Shows how the molecules interact.

  • Dot and Cross Diagram: Indicates the sharing of electrons.

  • Stick Diagram: 4 lines representing four covalent bonds.

Summary

• Mastery of drawing covalent bonds in H2O, NH3, and CH4 is crucial for understanding molecular structure and interactions in chemistry. Practicing these drawing skills will aid in exams and improve conceptual comprehension.