moleculefinder

Caesium

Cs132.905452 g/mol Calculated

Also called Cs.

The most reactive metal there is, liquid just above room temperature, and the atom whose vibration defines the length of a second. Element 55.

Sources and notes
  • The introductionfrom sourceMoleculeFinder curated
  • Other namesfrom sourceWikidataIts English label and aliases on Wikidata.
  • Formula and weightcomputedPubChem
  • 2D drawingcomputedPubChem structure, drawn by RDKit

Where you encounter it

A pure element or an engineered material, rather than an ingredient in a product.

Sources and notes
  • The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.

Properties and sources

Calculated by PubChem

Molecular formula
Cs
Molecular weight
132.905452 g/mol

Measured LD50, HSDB via PubChem

1,700 mg/kg pure caesium, mouse, another route

An LD50 is an animal study measurement, not a dose for a person.

Reported Hazard label (GHS), ECHA via PubChem

Danger Flammable pictogram (GHS02) and Corrosive pictogram (GHS05); hazard statements H260, H314, H318

Groups it belongs to

Category
Element & material
Family
Chemical elements
Hazard classes
Flammable, Corrosive, GHS Danger
SMILES[Cs]

PubChem CID 5354618 · Wikidata Q1108 · InChIKey TVFDJXOCXUVLDH-UHFFFAOYSA-N · Data refreshed

How MoleculeFinder sources and labels its data

Questions
What is Caesium?
The most reactive metal there is, liquid just above room temperature, and the atom whose vibration defines the length of a second. Element 55.
How toxic is Caesium?
The reported LD50 of Caesium is 1,700 mg/kg (mouse, other). An LD50 is an animal study measurement, not a dose for a person. Its GHS hazard label carries the signal word Danger and the hazard pictograms Flammable and Corrosive. from sourcefrom source
What kind of molecule is Caesium?
Caesium has the formula Cs and a molecular weight of 132.905 g/mol. MoleculeFinder files it under chemical elements, in the element & material group. from sourcefrom sourcefrom sourcefrom source
What else is Caesium called?
Caesium is also called Cs. from source
Sources and notes
  • Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
  • LD50from sourceHSDB via PubChem
  • Hazard labelfrom sourceECHA via PubChemThe label combines these classifications.
  • ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
  • Data refreshedfrom sourceMoleculeFinder2026-11-09