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Basic Information | Atomic Structure | Isotopes | Related Links | Citing This Page

Basic Information

Name: Cesium
Symbol: Cs
Atomic Number: 55
Atomic Mass: 132.90546 amu
Melting Point: 28.5 °C (301.65 K, 83.3 °F)
Boiling Point: 678.4 °C (951.55005 K, 1253.12 °F)
Number of Protons/Electrons: 55
Number of Neutrons: 78
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 1.873 g/cm³
Color: silver
British Spelling: Caesium
IUPAC Spelling: Caesium

Atomic Structure

Number of Energy Levels: 6

First Energy Level:

Second Energy Level:

Third Energy Level:

Fourth Energy Level:

Fifth Energy Level:

Sixth Energy Level:

Isotopes

Isotope	Half Life
Cs-126	1.6 minutes
Cs-129	1.3 days
Cs-131	9.7 days
Cs-132	6.4 days
Cs-133	Stable
Cs-134	2.1 years
Cs-134m	2.9 hours
Cs-135	2300000.0 years
Cs-136	13.2 days
Cs-137	30.2 years
Cs-138	32.2 minutes
Cs-139	9.3 minutes

Facts

Date of Discovery: 1860
Discoverer: Fustov Kirchoff
Name Origin: From the Latin word caesius (sky blue)
Uses: removes air traces in vacuum tubes
Obtained From: pollucite, lepidolite

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