Crystal Forces 3D

See how attraction, repulsion, bonding, and thermal motion hold solids together.

Stable lattice

Drag to rotate crystal • Shift-drag to pan • wheel or pinch to zoom • tap a particle

Mode

Solid examples

Conditions

Temperature150 K

Compression0%

Bond strength1.00×

Show forces

attractiverepulsivenet forceexternal pressure

Oppositely charged ions attract. Electron-cloud overlap creates strong short-range repulsion. At equilibrium these effects balance.

Run & 3D camera

Simulation speed1×

Horizontal rotation315°

Camera tilt32°

Separate layers0%

Zoom1.00×

Particle focus

No particle selectedFree camera

Position: —Neighbors: —Net force: —Energy: —

Live lattice data

Mean spacing

1.00 a

Repulsive force

1.00

Attractive force

1.00

Order index

100%

potential energykinetic energy

Teacher / Demo tools

Lattice columnsParticle massDefect siteImpulse

Learning objectives

Describe the ordered arrangement of particles in a solid.
Explain why solid particles vibrate but remain near equilibrium positions.
Compare attractive, repulsive, bonding, thermal, and external forces.
Relate temperature and compression to particle motion and spacing.
Compare ionic, metallic, molecular, and covalent solids.

Forces inside a solid

Attraction pulls neighboring particles together through electrical interactions: ionic charge, shared electrons, metallic electrons, or molecular attractions.

Repulsion rises sharply when electron clouds overlap. This prevents particles from collapsing into one another.

Equilibrium occurs where inward attraction and outward repulsion balance, giving the solid a preferred spacing.

Educational model: neighboring particles follow a two-part potential. A longer-range attractive term pulls them together; a steep short-range repulsive term pushes them apart. Temperature adds vibration, while compression supplies external force.

Compare the examples

Ionic salt: attraction between positive and negative ions plus short-range cloud repulsion.
Metal: positive ion cores are bound by mobile electrons; cores repel at close range.
Ice: covalent bonds hold each water molecule together and hydrogen bonds organize molecules.
Diamond: strong directional covalent bonds create a rigid network.

Suggested experiments

Raise temperature and observe vibration amplitude and lattice order.
Compress the crystal and compare repulsion with attraction.
Focus a particle and switch individual force arrows on and off.
Add a vacancy and observe how neighbors relax toward the empty site.
Compare bond strength in ice and diamond.

Guided investigations

1. Find equilibrium

Select Ionic salt and focus a central particle.
Pause and turn on attraction, repulsion, and net force.
Increase compression slowly.
Record where the red repulsive arrows begin to dominate.

2. Temperature and order

Set temperature to 0 K and observe fixed lattice sites.
Raise it to 300 K, then 900 K.
Compare kinetic energy and the order index.
Explain why the mean positions remain ordered even while particles vibrate.

3. See the full 3D lattice

Drag horizontally to rotate the crystal.
Change camera tilt from 20 to 70 degrees.
Separate the layers, then identify vertical neighbors.
Reset the view and compare coordination in each material.

Structure, defects, and properties

A crystal is a repeating three-dimensional pattern called a lattice. A particle's coordination number counts its nearest neighbors. Surface particles have fewer neighbors than particles inside the crystal.

A vacancy is a missing particle. A substitutional defect replaces one particle with another type. Defects change strength, electrical behavior, diffusion, and color.

Common misconception: particles in a solid are not motionless. Above absolute zero they vibrate continuously about equilibrium positions. The solid keeps its shape because restoring forces pull displaced particles back.

From forces to properties

Steeper force changes produce a stiffer solid.
Strong bonds usually increase melting temperature.
Mobile metallic electrons support electrical conduction.
Directional covalent networks can be extremely hard.
Hydrogen-bonded structures can be open and less dense.

Think like a scientist

Which evidence in the graph shows energy moving between potential and kinetic forms?
Why does compression increase stored potential energy?
How would a surface particle's force balance differ from an interior particle?
Which controls change the model itself, and which only change the camera?
What observation would distinguish thermal vibration from permanent lattice failure?