covalent bonding

Covalent Bonding Model

  • Covalent bonding occurs when non-metal atoms share electrons.

  • Understanding valence shell electron arrangements is key to predicting molecule formation.

Stability and the Octet Rule

  • Atoms strive for an outer shell of eight electrons for stability (octet rule).

  • Non-metal atoms commonly share electrons, leading to stable molecules rather than individual atoms.

  • Molecular substances are neutral and cannot conduct electricity due to the lack of free-moving charged particles.

Types of Covalent Bonds

Single Covalent Bonds

  • Formed by sharing two electrons (one from each atom).

  • Example 1: Hydrogen

    • Hydrogen atoms share to form H2, where the electrons spend more time between nuclei, creating a stable molecule.

  • Example 2: Chlorine

    • Chlorine atoms share to form Cl2, achieving octet configuration.

    • Illustrates application of the octet rule.

Lewis Structures

  • Represent molecules, showing valence shell electrons involved in bonding.

  • Distinguish between bonding electrons and non-bonding electrons (lone pairs).

Triple Covalent Bonds

  • Occurs when three electron pairs are shared.

  • Example: Nitrogen (N2)

    • Strong and relatively unreactive due to triple covalent bond.

    • Essential for living organisms; primarily found in proteins.

  • Nitrogen Fixation: Microorganisms convert N2 into soluble compounds for plant absorption.

  • Fritz Haber's Process: Converts nitrogen and hydrogen to ammonia for fertilizers.

Molecular Compounds

Diatomic Molecules

  • Contain two atoms (e.g., H2, Cl2).

  • Example: Hydrogen Chloride (HCl)

    • Formed through sharing between H and Cl, resulting in single covalent bond.

Polyatomic Molecules

  • Composed of more than two atoms.

  • Example 1: Water (H2O)

    • Oxygen shares electrons with two hydrogen atoms.

  • Example 2: Methane (CH4)

    • Carbon requires four shared electrons from hydrogen atoms for stability.

  • Example 3: Ethene (C2H4)

    • Double bond between carbon atoms, with single bonds to hydrogen.

Worked Example: Lewis Structures

  • Hydrogen Sulfide (H2S)

    • Sulfur (S) configuration: 2,8,6; requires 2 electrons.

    • Hydrogen (H) configuration: 1; requires 1 electron.

      • Lewis structure illustrates bonding and non-bonding pairs.