Lecture Notes: Ionic and Covalent Bonding

Introduction to Bonding

• Types of Chemical Bonds
  • Ionic Bonds
  • Covalent Bonds
• Role of Electronegativity
  • Tendency of an atom to attract electrons in a bond.
  • Measured using the Pauling scale, increases up a group and to the right across a period on the periodic table.

Ionic Bonds

• Occurs when one atom gives up electrons to another.
• Results in one atom/molecule becoming positively charged and the other negatively charged.
• Attraction between positive and negative charges holds them together.

Covalent Bonds

• Occurs when two atoms share a pair of electrons.
• Nonpolar Covalent Bonds
  • Electronegativity difference: 0 to 0.4
  • Electrons shared equally.
• Polar Covalent Bonds
  • Electronegativity difference: 0.4 to 1.9
  • Electrons not shared equally, greater electronegativity atom pulls more electrons.

Determining Bond Type

• Electronegativity Difference
  • Nonpolar Covalent: Difference ≤ 0.4
  • Polar Covalent: 0.4 < Difference ≤ 1.9
  • Ionic: Difference > 1.9

Examples

• Carbon-Hydrogen Bond
  • Electronegativity difference: 0.3
  • Type: Nonpolar Covalent
• Fluorine-Hydrogen Bond
  • Electronegativity difference: 1.9
  • Type: Polar Covalent
• Oxygen-Sodium Bond
  • Electronegativity difference: 2.6
  • Type: Ionic

Octet Rule

• Atoms form bonds to achieve stability.
• Stability typically achieved with 8 valence electrons.
• Noble Gases
  • Naturally stable due to having 8 valence electrons (except helium).
• Examples of Octet Rule
  • Chlorine becomes chloride ion by gaining an electron.
  • Sodium loses an electron to maintain a stable configuration.

Conclusion

• Understanding bond types and the role of electronegativity is crucial in determining chemical reactions and properties.
• The octet rule explains why atoms form certain bonds, aiming to achieve a stable electron configuration.