This key facts covers Key Facts to Memorise within Ionic Compounds for GCSE Chemistry. Revise Ionic Compounds in Bonding & Structure for GCSE Chemistry with 20 exam-style questions and 20 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 7 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 7 of 12
Practice
20 questions
Recall
20 flashcards
📌 Key Facts to Memorise
- Giant ionic lattice = regular 3D arrangement of alternating positive and negative ions
- No molecules — the whole crystal is one continuous structure
- High melting/boiling points — many strong electrostatic forces need lots of energy to break
- Solid: no conduction — ions fixed in position, cannot move
- Molten/dissolved: conducts — ions free to move and carry charge
- Brittle — force causes layers to shift, like charges repel, structure shatters
- Higher charges = higher melting point (MgO > NaCl)
- Smaller ions = higher melting point (ions closer = stronger attraction)
Quick Check: Predict whether KCl or MgO would have the higher melting point. Give a reason.
MgO has the higher melting point. Mg²⁺ and O²⁻ have charges of 2+ and 2-, while K⁺ and Cl⁻ have charges of only 1+ and 1-. Higher charges mean stronger electrostatic attractions, requiring more energy to overcome.