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Information valid for Ba-137 unless otherwise noted

Basic Information

Symbol: Ba
Atomic Number: 56
Mass: 137.327
Melting Point: 725.0 C
Boiling Point: 1140.0 C
Number of Protons/Electrons: 56
Number of Neutrons: 81
Classification: Alkaline Earth
Crystal Structure: Cubic
Density @ 293 K: 3.51 g/cm3
Color: Silver

Atomic Structure

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

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


Isotope Half Life
Ba-130 Stable
Ba-131 11.7 days
Ba-132 Stable
Ba-133 10.5 years
Ba-133m 1.6 days
Ba-134 Stable
Ba-135 Stable
Ba-135m 1.2 days
Ba-136 Stable
Ba-137 Stable
Ba-137m 2.6 minutes
Ba-138 Stable
Ba-139 1.4 hours
Ba-140 12.8 days
Ba-141 18.3 minutes
Ba-142 10.7 minutes


Date of Discovery: 1808
Discoverer: Sir Humphrey Davy
Name Origin: From the Greek word barys (heavy)
Uses: No uses known
Obtained From: barytine, whiterite