The chemical symbol "Rb" stands for the element rubidium. A standard periodic table of elements lists the atomic number of rubidium, 37, and the standard atomic weight of rubidium, 85.46 atomic mass units.
Rubidium is located in Group 1 on the periodic table of elements, also known as the alkali metal group. It was discovered by Robert Bunsen and Gustav Kirchhoff. It is soft with silver and white coloring. It has a melting point of 102.76 degrees Fahrenheit and a boiling point of 1,270 degrees Fahrenheit, and it ignites spontaneously when exposed to air. In a flame test, rubidium burns purple.