Rubidium is a chemical element that is part of group 1 of the periodic table, which means it shares some similar properties with other elements like sodium and potassium. It has the symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metal that is highly reactive and can catch fire when it comes into contact with air or water. It can be found in small amounts in some minerals such as lepidolite, pollucite, and carnallite. Rubidium has a number of applications in various fields, such as electronics, physics, and medicine. For example, it can be used to make highly sensitive sensors, as well as in the production of photocells and vacuum tubes.