Lesson 4.4: Covalent Bonds

Introduction to Covalent Bonds

• Covalent bonds occur when atoms share electrons to form molecules.
• Example: Two hydrogen atoms.
  • Each hydrogen atom has a proton (positive charge) and an electron (negative charge) in its first energy level.
  • Opposite charges attract, leading the electrons to be shared by both atoms.
  • The first energy level can hold a maximum of two electrons.
  • Sharing allows both hydrogen atoms to achieve stability (full outer shell).

Example: Water Molecule Formation

• Involves two hydrogen atoms and one oxygen atom.
• Focus on valence electrons (outer energy level electrons) during bonding.
• Hydrogen Atoms:
  • Each has one electron in its first shell and wants another to be stable.
  • A stable outer shell for hydrogen is filled with two electrons.
• Oxygen Atom:
  • Has six electrons in its second energy level.
  • Wants to fill the second energy level with eight electrons.
• Formation:
  • Oxygen pulls in the electrons from both hydrogen atoms.
  • Resulting in a water molecule: H₂O.
  • Each hydrogen has a full outer shell, and oxygen is now stable with eight electrons in its outer shell.

Example: Oxygen Molecule Formation

• Involves two oxygen atoms.
• Each oxygen atom has six valence electrons.
• To be stable, they need a full outer shell of eight electrons.
• Double Bond:
  • Each oxygen atom shares two electrons with the other.
  • Results in a double bond, forming an O₂ molecule.
  • This double bond allows for stability and full outer electron shells.
  • Oxygen is often found as a diatomic molecule (O₂) in nature, not as single atoms.

Summary

• Covalent bonds involve the sharing of electrons between atoms.
• Sharing achieves stability by filling the outer electron energy levels.
• Key examples include the formation of water (H₂O) and oxygen (O₂) molecules.
• Covalent bonding is crucial for molecule stability and occurs to reach a stable electron configuration.