Beryllium is the chemical element with the symbol Be and atomic number 4. Because any beryllium synthesized in stars is short-lived, it is a relatively rare element in both the universe and in the crust of the Earth. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl (aquamarine, emerald) and chrysoberyl. As a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal.Symbol: Be
Atomic number: 4
Electron configuration: [He] 2s2
Electrons per shell: 1,2
Atomic mass: 9.012182 ± 0.000003 u
Discoverers: Louis Nicolas Vauquelin