Knowledge Organiser: Ionic Bonding
Key Terms
- Ionic bond: electrostatic attraction between oppositely charged ions
- Cation (+): metal loses electrons
- Anion (-): non-metal gains electrons
- Electron transfer: electrons move from metal to non-metal
- Electrostatic attraction: force between opposite charges
Must-Know Facts
- Ionic bonding occurs between metals and non-metals
- Metals LOSE electrons → positive ions (cations)
- Non-metals GAIN electrons → negative ions (anions)
- Both ions achieve noble gas electron configuration
- Group 1 → +1, Group 2 → +2, Group 6 → -2, Group 7 → -1
- Dot-cross: outer shell only, brackets, charge outside
Key Equations
- Na → Na⁺ + e⁻ (metal loses electron)
- Cl + e⁻ → Cl⁻ (non-metal gains electron)
- Mg → Mg²⁺ + 2e⁻ (Group 2 loses 2 electrons)
- O + 2e⁻ → O²⁻ (Group 6 gains 2 electrons)
Common Mistakes
- Saying ionic bonding involves sharing electrons: Ionic = electron TRANSFER; covalent = electron SHARING — never confuse these
- Drawing ions without brackets and charges: Dot-cross diagrams for ionic compounds need square brackets with the charge written outside
- Wrong ion charges: Learn Group 1 = +1, Group 2 = +2, Group 6 = −2, Group 7 = −1
- Including inner shell electrons in dot-cross: Only draw the outer shell electrons in ionic bonding diagrams
Memory Aid
- Group 1 → +1 (e.g., Na⁺)
- Group 2 → +2 (e.g., Mg²⁺)
- Group 6 → -2 (e.g., O²⁻) — 8 - 6 = 2 short
- Group 7 → -1 (e.g., Cl⁻) — 8 - 7 = 1 short