Beryllium, atomic number 4, atomic weight 9.012182, is the lightest alkaline earth metal element. It was discovered in 1798 by the French chemist Walkerland during chemical analysis of beryl and emeralds. In 1828, the German chemist Weiler and the French chemist Bixi reduced molten beryllium chloride with potassium metal to obtain pure beryllium. Its English name is named after Weller. The content of beryllium in the earth’s crust is 0.001%, and the main minerals are beryl, beryllium and chrysoberyl. Natural beryllium has three isotopes: beryllium-7, beryllium-8, and beryllium-10.

Beryllium is a steel gray metal; melting point 1283°C, boiling point 2970°C, density 1.85 g/cm³, beryllium ion radius 0.31 angstroms, much smaller than other metals.

The chemical properties of beryllium are active and can form a dense surface oxide protective layer. Even in red heat, beryllium is very stable in air. Beryllium can not only react with dilute acid, but also dissolve in strong alkali, showing amphoteric. Oxides and halides of beryllium have obvious covalent properties, beryllium compounds are easily decomposed in water, and beryllium can also form polymers and covalent compounds with obvious thermal stability.

Metal beryllium is mainly used as a neutron moderator in nuclear reactors. Beryllium copper alloys are used to make tools that do not produce sparks, such as key moving parts of aero-engines, precision instruments, etc. Beryllium has become an attractive structural material for aircraft and missiles due to its light weight, high modulus of elasticity and good thermal stability. Beryllium compounds are toxic to the human body and are one of the serious industrial hazards.