Differences Between Polar and Non-Polar Covalent Bonds

Introduction

• Covalent Bond: Electrons are shared between atoms.
  • Example: Two Hydrogen atoms (H-H).
• Ionic Bond: Electrons are transferred, forming positive and negative ions that attract each other.
  • Example: Sodium (Na) and Chlorine (Cl) form NaCl.
  • Cations: Positively charged ions.
  • Anions: Negatively charged ions.
  • Electrostatic Force: Attraction between oppositely charged ions creates the ionic bond.

Covalent Bonds

• Non-polar Covalent Bond: Equal sharing of electrons.
  • Example: Hydrogen gas (H-H).
  • Atoms have the same electronegativity.
• Polar Covalent Bond: Unequal sharing of electrons.
  • Example: Hydrogen Fluoride (H-F).
  • Different electronegativity values lead to partial charges.
  • Fluorine (4.0) attracts electrons more than Hydrogen (2.1).
• Electronegativity Difference:
  • Non-polar Covalent: 0 - 0.4
  • Polar Covalent: 0.5 - 1.9
  • Ionic: >1.9

Identifying Bond Types

• Ionic Bonds:
  • Composed of ions (positive and negative).
  • Typically between a metal and a non-metal.
• Polar vs Non-Polar Covalent Bonds:
  • Look at electronegativity values.
  • Example: Carbon (2.5) and Hydrogen (2.1) form a non-polar bond (difference = 0.4).
  • Example: Carbon (2.5) and Oxygen (3.5) form a polar bond (difference = 1.0).
• Additional Examples:
  • Sodium Fluoride (NaF): Ionic bond (difference = 3.1).

Problem Solving

1. Chlorine Molecule (Cl-Cl):
   • Non-polar Covalent (same non-metal atoms).
2. Carbon-Hydrogen Bond (C-H):
   • Non-polar Covalent (difference = 0.4).
3. Carbon-Oxygen Bond (C-O):
   • Polar Covalent (difference = 1.0).
4. Sodium Fluoride (NaF):
   • Ionic Bond (difference = 3.1).

Comparing Polarities

• Rules:
  • Elements far apart on periodic table = More polar.
  • Elements close on periodic table = Less polar.
• Examples:
  1. N-F vs P-F vs As-F: Arsenic-Fluorine bond is most polar due to distance on periodic table.
  2. C-F vs N-F vs O-F:
     • C-F: Most polar (difference = 1.5).
     • O-F: Least polar (difference = 0.5).