# FREEZING (DD-444)

> When water cools below 0 °C (32 °F), its molecules lock into a hexagonal crystal lattice held by hydrogen bonds, each molecule bonded to four neighbors. The lattice is more open than liquid water, so ice is about 9 percent less dense and floats, and water expands as it freezes. The footage shows an animation of water molecules forming ice.

- Department: Science
- First published: 2024-12-31
- Last updated: 2024-12-31
- Permalink: https://detailenjoyer.com/case/freezing/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-444-F01**: Hexagonal. _(Write-up · Exhibit A (Lattice))_
- **DD-444-F02**: Hydrogen bonds. _(Write-up · Exhibit B (Bonds))_

## Write-up

Ice floats because freezing water spreads out into an open lattice. Hydrogen bonds hold each molecule to four neighbors.

1. **Lattice**: Hexagonal.
2. **Bonds**: Hydrogen bonds.
3. **Neighbors**: Four per molecule.
4. **Density**: About 9% less dense.
5. **Expansion**: Water expands on freezing.

## Related case files

- [How Water Freezes (DD-468)](https://detailenjoyer.com/case/how-water-freezes/): I linked more on freezing water

## Reel vs. record

- **Note**: None needed.

## Video: FREEZING: Ice Floats Because Freezing Water Spreads Out Into an Open Lattice

- Duration: 28.8 s · Published: 2024-12-31
- File: https://detailenjoyer.com/assets/videos/DEPMLaAqCRV.mp4

### Transcript

Water molecules align to form ice [...] crystallization process where they arrange into a hexagonal lattice as temperatures drop below 0 °C or 32 °F. This alignment [is] due to hydrogen bonding, where each water molecule [bonds] to four others, creating a repeating and spacious pattern. The hexagonal structure results in ice being less dense than liquid water, [allowing] it to float. This unique molecular arrangement not only explains ice's buoyancy, [but also] contributes to its ability to expand as it freezes. NOW YOU KNOW!

## Questions & answers

**Q: What shape is the ice lattice?**  
A: Six-sided. _(Source: Write-up · Exhibit A (Lattice) · Wikipedia: Ice)_

**Q: What bonds hold it?**  
A: Water. _(Source: Write-up · Exhibit B (Bonds) · Wikipedia: Ice)_

**Q: Why does ice float?**  
A: Open lattice. _(Source: Write-up · Exhibit C (Neighbors) · Wikipedia: Ice)_

**Q: At what temperature does water freeze?**  
A: 32 °F. _(Source: Write-up · Exhibit D (Density) · Wikipedia: Ice)_

**Q: How many neighbors per molecule?**  
A: Tetrahedral. _(Source: Write-up · Exhibit E (Expansion) · Wikipedia: Ice)_

## Sources

- [Wikipedia: Ice](https://en.wikipedia.org/wiki/Ice)

## Cite this case file

Easterling, Marcus. "FREEZING." The Detail Department (DetailEnjoyer), case file DD-444, last updated Dec 31, 2024. https://detailenjoyer.com/case/freezing/