Three Main Types of Bonding
How atoms interact to achieve stable electron configurations through covalent, ionic, and metallic bonding
Chemical bonding is the force that holds atoms together in compounds. The type of bond depends on the elements involved and how they interact to achieve a stable electron configuration (octet rule).
Covalent Bonding
Definition: The sharing of at least one pair of electrons between non-metal atoms.
Formation
Forms when the difference in electronegativity between atoms is small. Neither atom strongly attracts electrons away from the other.
Sub-types
Properties
- Form molecules
- Low melting and boiling points
- Non-conductors of electricity (no free ions/electrons)
- Often gases, liquids, or low-melting solids at room temperature
Examples: H₂, O₂, N₂, H₂O, CO₂, CH₄
Ionic Bonding
Definition: The transfer of electrons from a metal to a non-metal, forming ions held by electrostatic attraction.
Formation
Forms when there is a large difference in electronegativity between atoms. Metal loses electrons (cation), non-metal gains electrons (anion).
Crystal Lattice
Ions pack in a regular repeating pattern:
Properties
- High melting and boiling points (strong electrostatic forces)
- Brittle - shatter when force is applied
- Conduct electricity when molten or dissolved in water (ions free to move)
- Do not conduct when solid (ions fixed in lattice)
Examples: NaCl, MgO, CaCl₂, KBr
Summary Table for Exams
| Feature | Covalent | Ionic | Metallic |
|---|---|---|---|
| Particles Involved | Non-metal atoms | Metals + Non-metals | Metal atoms |
| Electron Action | Sharing | Transfer | Delocalised "sea" |
| Structure | Molecules | Crystal Lattice | Metallic Lattice |
| Melting/Boiling Points | Low | High | Moderate to High |
| Electrical Conductivity | Poor (insulator) | Good when molten/aqueous | Excellent |
| Malleability/Ductility | Brittle (molecular) | Brittle | Malleable & Ductile |
Identify the Bond Type
Click on the correct bond type for each example:
Test Your Understanding
1. Which type of bonding involves a "sea of delocalised electrons"?
2. Ionic compounds conduct electricity when:
3. A triple bond shares how many electrons?
4. Which property is characteristic of metals?
Key Terms
Key Takeaways
- Covalent bonding: Non-metals share electrons (small EN difference) - forms molecules with low melting/boiling points
- Single bond (2 e⁻), Double bond (4 e⁻), Triple bond (6 e⁻)
- Ionic bonding: Metal transfers electrons to non-metal (large EN difference) - forms crystal lattice with high melting points
- Conduct electricity when molten or dissolved (ions free to move)
- Metallic bonding: Positive ions in a sea of delocalised electrons
- Excellent conductors, malleable, ductile, lustrous
- Bond type determines the properties of the compound
