3D Pi Bonds

Align · overlap · twist · explain

Mode

Orbital-overlap laboratory

Molecular example

Visual investigation

Orbital twist angle0°

Nuclear separation2.2 Å

Simulation speed1×

Drag empty space to rotate the view. Shift-drag to pan. Tap an orbital, bond, axis, or cloud for a short explanation.

Live relationships

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Tap a part to explain its role.

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Voice and language

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Narrator

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Narration volume100%

Embedded loudness-normalized narration can be captured by an external recorder using tab or system audio. No built-in recording controls are included.

Ready · 10 visual chapters.

Chapters

Learning objectives

Identify sideways p-orbital overlap as a pi bond.
Distinguish sigma and pi electron-density regions.
Explain why double bonds resist free rotation.
Count pi bonds in double and triple bonds.
Recognize conjugated and delocalized pi systems.

Key ideas

A pi bond forms when neighboring parallel p orbitals overlap sideways. Its electron density lies above and below the internuclear axis, with a nodal plane through the nuclei.

A double bond is 1σ + 1π. A triple bond is 1σ + 2π. Twisting lowers overlap approximately as cos² θ and raises energy approximately as sin² θ.

Try these experiments

Move the twist slider from 0° to 90° and watch overlap disappear.
Compare ethene, ethyne, and ethane.
Open Phase and Nodes, then switch between aligned and perpendicular orbitals.
Inspect benzene to see a continuous cloud above and below the ring.
Use Track Next Part while zooming and panning.

Questions for exploration

Why is rotation around a double bond difficult? Why are the two pi bonds in ethyne perpendicular? How does delocalization stabilize benzene?

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Ten independent pages. Works with touch, stylus, mouse, Android devices and interactive smart boards.