Cesium at Chemical Elements.com 

 

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

[Bohr Model of Cesium]  
Number of Energy Levels: 6

    First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 18
    Fifth Energy Level: 8
    Sixth Energy Level: 1

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