Beginner Topic 196 of 1102 Bonding & Molecular Structure
Ionic Solids
Ions arranged in a lattice, such as NaCl, with high melting points and brittleness.
Practise Bonding & Molecular Structure All Bonding & Molecular Structure topics
In-depth explanation of Ionic Solids
Ionic solids consist of cations and anions arranged in a regular lattice held together by strong electrostatic attraction. Common structures include the rock-salt arrangement of NaCl, where each ion has six nearest neighbours, and the caesium chloride arrangement, where each ion has eight. Because the lattice energy is high, ionic solids have high melting points and are hard, but they are brittle because shifting layers brings like charges together. They dissolve in polar solvents such as water and conduct electricity when molten or dissolved. Ionic solids are generally insoluble in nonpolar solvents.
Going deeper: Ionic Solids
Key ideas: Structure choice depends on the radius ratio: about 0.414 to 0.732 favours six-coordinate (rock salt), above 0.732 favours eight-coordinate (CsCl), 0.225 to 0.414 favours four-coordinate (zinc blende). NaCl: unit cell has 4 formula units, with coordination number 6:6. Compute density from unit cell volume: d equals Z times M divided by (N_A times a cubed).
Common mistakes and connections: Mistakes include saying ionic solids consist of molecules, mixing up CsCl with a body-centred lattice of one atom type (it is simple cubic with a two-ion basis), and miscounting ions in the unit cell. Links to lattice energy, radius ratio, unit cell calculations and solubility.
Visualization of Ionic Solids
In CsCl each Cs+ has eight Cl- neighbours in a body-centred arrangement, a different ionic structure from the six-coordinate NaCl lattice. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Sodium chloride has a coordination number of 6 for both Na+ and Cl- in its rock-salt lattice.
Frequently asked questions about Ionic Solids
What is Ionic Solids?
Ions arranged in a lattice, such as NaCl, with high melting points and brittleness.
Is Ionic Solids a beginner, intermediate or advanced topic?
Ionic Solids is a beginner topic in Bonding & Molecular Structure. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Ionic Solids?
Study these earlier topics in Bonding & Molecular Structure first: Water's Anomalous Properties, Covalent Network Solids, Molecular Solids.
What comes after Ionic Solids?
The next topics in Bonding & Molecular Structure are Metallic Solids and Allotropes of Carbon.
Can I practise Ionic Solids with quizzes?
Yes. The interactive lesson includes a self-check question on Ionic Solids, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Where Ionic Solids fits in Bonding & Molecular Structure
Ionic Solids is topic 81 of 104 in Bonding & Molecular Structure.