Make your own free website on


Information valid for Rb-85 unless otherwise noted

Basic Information

Symbol: Rb
Atomic Number: 37
Mass: 85.4678
Melting Point: 38.89 C
Boiling Point: 688.0 C
Number of Protons/Electrons: 37
Number of Neutrons: 48
Classification: Alkali Metal
Crystal Structure: Cubic
Density @ 293 K: 1.532 g/cm3
Color: silver

Atomic Structure

[Bohr Model of Rubidium]
Number of Energy Levels: 5

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


Isotope Half Life
Rb-81 4.57 hours
Rb-82 2.25 minutes
Rb-83 86.2 days
Rb-84 32.9 days
Rb-85 Stable
Rb-86 18.65 days
Rb-87 4.8E10 years
Rb-88 17.7 minutes
Rb-89 15.44 minutes
Rb-90 2.6 minutes
Rb-90m 4.3 minutes


Date of Discovery: 1861
Discoverer: R. Bunsen
Name Origin: From the Latin word rubidus (red)
Uses: catalyst, photocells
Obtained From: lithium production