1. 4
Berilio – Beryllium
Mass: 9,0122 u
Electron configuration: [He] 2s2
2, 2, s
Melting point: 1 560 K (1 287 °C)
Boiling point: 2 742 K (2 469 °C)
Density: 1848 kg/m3
Discovery: antiquity.
Beryllium is thechemical 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 mine-rals. Notable gemstones which contain
beryllium include beryl (aquamarine, esmerald) and chrysoberyl. As a
free element it is a steel-gray, strong, lightweight and brittle alkaline
earth metal.