Key facts
- Category
- Atoms
- Object class
- Atom
- Scale fact
- 520 pmdiameter
- Composition
- Cs-133: 55 protons, 78 neutrons, 55 electrons
Cesium Atom
520 pmdiameter
Visual creditscaleofspace.org / CC BY-NC 4.0
Details
Cesium is a large alkali-metal atom with a loosely held outer electron. The fixed frequency of a hyperfine transition in cesium-133 defines the SI second, linking atomic physics to every precise measurement of time.
The SI fixes the unperturbed ground-state hyperfine transition frequency of cesium-133 at exactly 9,192,631,770 hertz. Cesium atoms do not act as clocks on their own: a frequency standard prepares and interrogates them, then uses that reproducible transition to realize the second.
Links
- Editorial guides
- Wikipedia
- Cesium Atom on Wikipedia
- Preset views
Size neighbors
Objects near Cesium Atom on the scale
On the logarithmic size axis, Cesium Atom falls between Water Molecule and Coronene. The band uses nearby Atom records.
Shared physical scale
398pm
Sources
References for Cesium Atom
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Cesium Atom — Wikipedia
- Visual: scaleofspace.org / CC BY-NC 4.0
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About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.