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Information valid for Kr-84 unless otherwise noted

Basic Information

Symbol: Kr
Atomic Number: 36
Mass: 83.8
Melting Point: -157.2 C
Boiling Point: -153.4 C
Number of Protons/Electrons: 36
Number of Neutrons: 48
Classification: Noble Gas
Crystal Structure: Cubic
Density @ 293 K: 3.74 g/cm3
Color: colorless gas

Atomic Structure

[Bohr Model of Krypton]
Number of Energy Levels: 4

  1. First Energy Level: 2
    Second Energy Level: 8
    Third Energy Level: 18
    Fourth Energy Level: 8


Isotope Half Life
Kr-78 Stable
Kr-79 1.45 days
Kr-80 Stable
Kr-81 210000.0 years
Kr-82 Stable
Kr-83 Stable
Kr-83m 1.86 hours
Kr-84 Stable
Kr-85 10.73 years
Kr-85m 4.48 hours
Kr-86 Stable
Kr-87 1.27 hours
Kr-88 2.84 hours
Kr-89 3.15 minutes
Kr-90 32.3 seconds


Date of Discovery: 1898
Discoverer: Sir William Ramsey
Name Origin: From the Greek word kryptos (hidden)
Uses: Lighting
Obtained From: production of liquid air