Neutral atoms are ready.AtomsCharge 0Energy high

Lattice Energy Simulation

Charge, ionic radius, attraction, and crystal stability

Workspace

Crystal energy lab

Ion controls

Cation charge+1

Anion charge−1

Cation radius102 pm

Anion radius181 pm

Simulation speed1×

Camera zoom1×

Interaction sounds

Live values

Lattice energy−762 kJ/mol

Charge product1

Ion distance283 pm

Relative force1.00

1. Begin with separated gaseous ions

U = −138,935 × M × |z⁺z⁻| ÷ r₀ × (1 − 1/n)

The ions are far apart, so attraction has not yet lowered their potential energy. The zero reference represents fully separated gaseous ions.

Why it changesA lattice forms only when attractive interactions lower the energy enough to stabilize the solid.

Predict nextPress Assemble. The ions should accelerate inward and the energy marker should move downward.

Energy versus separation

Object focus

Tap an ion, attraction arrow, energy well, or lattice site.

Teacher tools

Teacher narration

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Narrator

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Ready. Embedded tab audio is available and microphone access is never used.

Chapter 1 of 80%

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For external recording, share this browser tab with tab audio enabled. The embedded narration is boosted and recordable; no microphone is requested.

Chapters

Learning objectives

Define lattice energy for gaseous ions forming an ionic solid.
Predict charge and radius effects.
Interpret the Born–Landé equation and energy graph.
Connect three-dimensional lattice geometry to stability.
Relate lattice energy to separation and melting behavior.

Key relationships

U = −138,935 × M × |z⁺z⁻| ÷ r₀ × (1 − 1/n)

Greater charge product makes the energy more negative. Smaller center-to-center distance also makes it more negative. The Madelung constant represents the full crystal geometry.

Suggested experiments

Compare LiF and KBr to isolate the radius effect.
Compare NaCl and MgO to reveal the charge effect.
Pull apart a strong lattice and watch energy rise toward zero.
Keep charge fixed while changing only one ionic radius.

Questions for exploration

Why is formation energy negative?
Why can a smaller ion increase melting point?
Why is one ion pair insufficient to describe a crystal?

Ionic challenge

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Teacher whiteboard

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