Caesium

Statistics:

• Name: Caesium
• Symbol: Cs
• Classification: Alkali Metals
• Atomic Number: 55
• Atomic Mass: 132.9054519 g/mol
• Density: 1.9 g/cm³
• Melting: 28.4°C
• Boiling: 690°C
• Protons & Electrons:55
• Neutrons:78
• Discovered: 1860
• Discovered By: Kirchhoff and Bunsen
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Electrons Per Energy Level:

• Level 1: 2
• Level 2: 8
• Level 3: 18
• Level 4: 18
• Level 5: 8
• Level 6: 1

Isotopes:

Isotope: Half-life

• ¹²⁶Cs: 1.64 minutes
• ¹²⁹Cs: 32.06 hours
• ¹³¹Cs: 9.689 days
• ¹³²Cs: 6.479 days
• ¹³³Cs: stable
• ¹³⁴Cs: 2.0648 years
• ^134m1Cs: 2.903 hours
• ¹³⁵Cs: 2.3e+6 years
• ¹³⁶Cs: 13.16 days
• ¹³⁷Cs: 30.07 years
• ¹³⁸Cs: 33.41 minutes
• ¹³⁹Cs: 9.27 minutes

Brief Summary

Caesium is a Alkali Metals with the symbol 'Cs' and contains 55 Protons & Electrons with 78 neutrons in the nucleus of the atom. Caesium has an atomic mass of 132.9054519 g/mol and, at a temperature of 20°C, has a density of 1.9 g/cm³. It will melt at a temperature of 28.4°C and boil at 690°C.

Caesium was discovered by Kirchhoff and Bunsen in 1860 and is named 'Caesium' Latin word "caesius" meaning "sky blue".

Some common usages for Caesium: removes air traces in vacuum tubes.

Definitions and Notes

Density listed is at a temperature of 20°C.

Isotopes are forms of an element who have the same atomic number but different mass because they contain different number of neutrons.

Half-life is the time required for a quantity of a subject to fall to half of its current quantity.

MLA Citing Format

Caesium :: Cs :: 55 - Chemical Element. 22 Nov. 2008 <http://www.chemicalelement.com/element/caesium.html>.