Ionic vs Covalent Bonding

Overview

• Ionic Bonding

  • Involves transfer of electrons from one element to another.
  • Typically contains ions.
  • Example: Reaction between sodium (Na) and chlorine (Cl).

• Covalent Bonding

  • Involves sharing of electrons.
  • Two types: Polar covalent and Non-polar covalent.

Ionic Bonding

• Sodium and Chlorine Reaction
  • Sodium (Na):
    • Has one valence electron.
    • Located in Group 1a of the periodic table (alkali metals).
    • Metals tend to give away electrons, forming positively charged ions.
  • Chlorine (Cl):
    • Has seven valence electrons.
    • Located in Group 7a (halogens, reactive nonmetals).
    • Nonmetals tend to receive electrons, forming negatively charged ions.
  • Process:
    • Sodium transfers its valence electron to chlorine.
    • Sodium becomes positively charged, chlorine becomes negatively charged.
    • Electrostatic attraction between opposite charges forms the ionic bond.

Covalent Bonding

• Basics

  • Involves sharing of electrons.
  • Example: Two hydrogen atoms sharing electrons to form H2.

• Types of Covalent Bonds

  • Non-polar Covalent Bonds:
    • Electrons are shared equally.
    • Example: Bond between two hydrogen atoms.
  • Polar Covalent Bonds:
    • Electrons are shared unequally.
    • Example: Bond between hydrogen and fluorine.
    • Electronegativity difference causes uneven electron distribution, forming a dipole.
    • Fluorine acquires a partial negative charge; hydrogen a partial positive.

Electronegativity

• Definition: The ability of an atom to attract electrons toward itself.
• Fluorine:
  • Highly electronegative.
  • Attracts electrons strongly.
• Polar vs. Non-polar:
  • Polar: Unequal sharing due to electronegativity difference (e.g., hydrogen and fluorine).
  • Non-polar: Equal sharing (e.g., two chlorine atoms).

Examples and Practice

• Ionic Bonds:

  • Magnesium oxide (MgO):
    • Magnesium is a metal, oxygen is a nonmetal; forms ionic bonds.

• Non-polar Covalent Bonds:

  • Two chlorine atoms or carbon-hydrogen bonds.

• Polar Covalent Bonds:

  • Difference in electronegativity ≥ 0.5.
  • Example: HBr (hydrogen bromide).

Identifying Bond Types

• Ionic Compounds:

  • Metal and nonmetal combination.
  • Examples: Sodium fluoride, calcium sulfide.
  • Metals on left side of periodic table; nonmetals on right.

• Covalent Compounds:

  • Check electronegativity difference.
  • Use periodic table or designated charts for values.

Key Takeaways

• Ionic bonding involves the transfer of electrons.
• Covalent bonding involves the sharing of electrons.
• Electronegativity difference helps determine if a bond is polar or non-polar.

Important Concepts:

• Valence Electrons: Electrons in the outermost energy level.
• Electrostatic Attraction: Force that holds ions together in ionic bonds.
• Dipole: A molecule with an uneven distribution of charges.

End of lecture. Review these key points to understand the differences between ionic and covalent bonding.