By-product of lithium and cesium refining; Cs and Rb are separated by fractional crystallization of their alum salts. Metallic Rb comes from reducing RbCl with Ca under vacuum.
Research Elements Rb · atomic number 37 Alkali metal · period 5, group 1 [Kr] 5s1 Shells: 2, 8, 18, 8, 1 Valence electrons: 1 in the outer shell (5s1) Green dots are the outer shell's s and p electrons. Softer green dots are the d electrons of transition metals, and the d and f electrons of lanthanides and actinides: they often take part in bonding, but not always. Grey dots are the core. Ground-state configuration from the NIST Atomic Spectra Database (A. Kramida, Yu. Ralchenko, J. Reader and the NIST ASD Team). Abundance is the mole fraction of the element found as that isotope on Earth; digits in parentheses are the uncertainty in the last digits. Masses and abundances from NIST, Atomic Weights and Isotopic Compositions (J. S. Coursey, D. J. Schwab, J. J. Tsai and R. A. Dragoset, National Institute of Standards and Technology).Rubidium
Electrons
How it's obtained
Natural isotopes
Isotope Relative atomic mass Abundance 85Rb 84.9117897379(54) 0.7217(2) 87Rb 86.9091805310(60) 0.2783(2)