Study Notes on Covalent and Ionic Bonds

Covalent Bonds

• Covalent bonds are characterized by:

  • The sharing of electrons between atoms.
  • Typically occurring between two nonmetals.

• Differences in Electronegativity:

  • Covalent bonds form when there is not a sufficient difference in electronegativity to gain or lose electrons.
  • Variation in electronegativity within a covalently bonded molecule may lead to the molecule being either polar or nonpolar.

• Polar Covalent Compounds:

  • In polar covalent compounds, there is a distribution of electrical charge leading to a partial positive and partial negative charge.
  • Example: Water (H₂O) is a polar molecule:
    • The hydrogen atoms exhibit partial positive charges.
    • The oxygen atom exhibits a partial negative charge due to its high electronegativity, which pulls shared electrons closer to itself.
  • Although polar covalent molecules have charged sides, they maintain an overall neutral charge.

Ionic Bonds

• Ionic bonds form through:

  • The complete transfer of electrons between metals and nonmetals.
  • Metals typically lose electrons (cations) while nonmetals gain electrons (anions).
  • A significant difference in electronegativity is required for ionic bond formation.

• Charge Creation:

  • After the transfer of electrons, the resulting atoms become charged particles (cations and anions).

• General Characteristics of Ionic Bonds:

  • Typically observed between metals (left side of the periodic table) and nonmetals (right side).
  • Example of ionic compound behavior can be seen in reactions involving compounds formed between these two classes of elements.