4Berilio – BerylliumMass: 9,0122 uElectron configuration: [He] 2s22, 2, sMelting point: 1 560 K (1 287 °C)Boiling point: 2 742 K (2 469 °C)Density: 1848 kg/m3Discovery: antiquity.Beryllium is thechemical element with the symbol Be and atomic number4. Because any beryllium synthesized in stars is short-lived, it is arelatively rare element in both the universe and in the crust of theEarth. It is a divalent element which occurs naturally only in combinationwith other elements in mine-rals. Notable gemstones which containberyllium include beryl (aquamarine, esmerald) and chrysoberyl. As afree element it is a steel-gray, strong, lightweight and brittle alkalineearth metal.