Chemical Bond
Summary: A strong force of attraction holding atoms together in a compound or element. Tags: igcse chemistry keyword Created: 2026-08-06
A chemical bond is a strong force of attraction that holds atoms together, keeping them joined in elements and compounds. Bonds form between atoms because they lower the energy of the atoms and, at IGCSE level, because atoms tend to achieve a stable outer electron shell (usually the noble-gas configuration of 8 outer electrons, or 2 for the first shell). There are three types of bonding at IGCSE:
- Ionic bonding: the electrostatic attraction between oppositely charged ions, formed when electrons are transferred from a metal atom to a non-metal atom (e.g. sodium chloride).
- Covalent bonding: atoms share a pair of electrons, usually between non-metal atoms (e.g. water, carbon dioxide, diamond).
- Metallic bonding: the electrostatic attraction between positive metal ions in a lattice and a sea of delocalised electrons (e.g. iron, copper).
The key exam point is being able to explain the type of bonding and structure from the properties of a substance — for example, high melting points suggest ionic or giant covalent bonding, while poor solubility and no conductivity in any state suggest giant covalent, and the ability to be hammered into shape suggests metallic bonding.
Sources
- Cambridge IGCSE Chemistry 0620 Syllabus (2023-2025), Cambridge Assessment International Education
Common Misconceptions
| Misconception | Reality |
|---|---|
| Ionic bonding involves sharing electrons | Ionic bonding involves transfer of electrons; sharing of pairs is covalent bonding |
| Atoms bond to become ‘full’ in a physical sense | The ‘full shell’ is a model for the stable arrangement; at IGCSE, bonding is explained via electrostatic attraction and shared pairs |
| Chemical bonds are physical hooks joining atoms | A chemical bond is a force of attraction (electrostatic or shared-electron pair), not a physical link |