Study Notes
Covalent bonding involves the sharing of electrons between non-metal atoms to form stable compounds, characterized by the electrostatic attraction between nuclei and shared electrons. Coordinate (dative covalent) bonding occurs when one atom provides both electrons for the bond.
- Covalent Bonding — a chemical bond formed by the sharing of electrons between non-metal atoms. Example: Water (H₂O) has covalent bonds between hydrogen and oxygen.
- Coordinate (Dative) Bonding — a type of covalent bond where one atom donates both electrons. Example: In ammonium ion (NH₄⁺), nitrogen donates a pair of electrons to bond with hydrogen.
- Orbital Overlap — the interaction of atomic orbitals to form σ and π bonds. Example: Ethylene (C₂H₄) has two σ bonds and two π bonds.
- Hybridisation — the mixing of atomic orbitals to form new hybrid orbitals. Example: In methane (CH₄), carbon undergoes sp³ hybridisation.
- Bond Energy — the energy required to break a mole of bonds in the gaseous state. Example: The bond energy of an H-H bond is about 436 kJ/mol.
- Bond Length — the distance between the nuclei of two bonded atoms. Example: The bond length of a C-H bond is approximately 109 pm.
Exam Tips
Key Definitions to Remember
- Covalent Bonding: Sharing of electrons between non-metal atoms.
- Coordinate Bonding: A covalent bond where one atom provides both electrons.
- Hybridisation: Mixing of atomic orbitals to form hybrid orbitals.
- Bond Energy: Energy needed to break a mole of bonds in the gaseous state.
- Bond Length: Distance between nuclei of bonded atoms.
Common Confusions
- Confusing covalent bonds with ionic bonds, which involve electron transfer.
- Misunderstanding that coordinate bonds are a type of covalent bond.
Typical Exam Questions
- What is a covalent bond? A covalent bond is formed by the sharing of electrons between non-metal atoms.
- How does coordinate bonding differ from regular covalent bonding? In coordinate bonding, one atom provides both electrons for the bond.
- What is the significance of bond energy? Bond energy indicates the strength of a bond and the energy required to break it.
What Examiners Usually Test
- Understanding of the octet rule and exceptions in period 3 elements.
- Ability to identify and describe examples of covalent and coordinate bonds.
- Knowledge of how hybridisation affects molecular shape and bonding.