Beryllium
Beryllium is a chemical element with symbol Be and atomic number 4. It is created through stellar nucleosynthesis and is a relatively rare element in the universe. It is a divalent element which occurs naturally only in combination with other elements in minerals.
Identity
- Atomic mass
- 9.012 u
- Category
- Alkaline earth metals
- Group
- 2
- Period
- 2
- Block
- s
- Oxidation States
- +2
- Phase (25 °C)
- Solid
- Appearance
- white-gray metallic
Electronic Structure
- Electron configuration
- 1s2 2s2
- Short configuration
- [He] 2s2
- Electrons per shell
- 2, 2
- Electronegativity (Pauling)
- 1.57
- Electron affinity
- -48 kJ/mol
- 1st ionization energy
- 900 kJ/mol
- Ionization energies
- 900 · 1757 · 14849 · 21007 kJ/mol
Physical properties
- Melting point
- 1286.8 °C (1560 K)
- Boiling point
- 2468.8 °C (2742 K)
- Density
- 1.85 g/cm³
- Molar heat capacity
- 16.4 J/(mol·K)
Chemical behavior of beryllium
Beryllium has two valence electrons ([He] 2s2) and forms exclusively the Be2+ cation, tiny and with very high charge density. This smallness polarizes anions so strongly that its bonds show marked covalent character, an exception among alkaline earth metals, with polymerized insoluble compounds. It is also amphoteric: its oxide and hydroxide dissolve in both acids and bases. Its oxidation state is invariably +2.
Reactivity
2 Be + O₂ → 2 BeO
When heated it burns with white light forming the oxide; at room temperature it does not react because a thin BeO layer passivates it, as with aluminium.
Be + 2 HCl → BeCl₂ + H₂
Non-oxidizing acids dissolve it releasing hydrogen and giving soluble beryllium salts. Concentrated nitric acid, in contrast, passivates it.
Be + 2 NaOH → Na₂BeO₂ + H₂
When hot, concentrated bases also attack it forming soluble beryllates. This dual reactivity defines an amphoteric metal.
Be + F₂ → BeF₂
With fluorine it reacts directly giving the fluoride, a polymeric solid that underlies the molten salts of some reactors.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Beryllium oxide | BeO | High thermal conductivity ceramic for electronics; toxic dust |
| Beryllium fluoride | BeF₂ | Reactor molten salts and ultraviolet optics |
| Beryl | Be₃Al₂(SiO₃)₆ | Main ore; its gem varieties are emerald and aquamarine |
| Beryllium copper | Cu-Be | Hard, spark-free, non-magnetic alloy for tools and springs |
Electron shell distribution
View in the atom builderIsotopes
All natural beryllium is beryllium-9 (9Be), with five neutrons: it is monoisotopic. Trace cosmogenic isotopes exist: beryllium-10 (10Be), with a 1.39-million-year half-life, dates ice and sediments, and beryllium-7 (7Be), of 53 days, traces atmospheric movements.
Occurrence and production
It is a rare metal (2-6 ppm of the crust) that never appears free. Its ores are beryl and bertrandite Its ores are beryl and bertrandite and bertrandite, mined mainly in the United States (Spor Mountain, Utah), China and Brazil. The metal is obtained by reducing the fluoride with magnesium or by electrolysis of molten salts.
History and origin of the name
Louis-Nicolas Vauquelin discovered it in 1798 analyzing beryl and emerald, calling it glucinium for the sweet taste of its salts, a test unthinkable today for its toxicity. Wohler and Bussy isolated it as a metal in 1828, and the name beryllium, from the mineral beryl, prevailed.
Applications and relevance of beryllium
Uses of the element
Its lightness, stiffness and X-ray transparency suit it for X-ray tube windows, space mirrors such as the Webb telescope's, aerospace parts and neutron moderators in reactors. Alloyed with copper it gives spark-free tools for explosive atmospheres.
Uses of its compounds
The oxide is used in heat-dissipating electronic ceramics; cut beryl gives emeralds and aquamarines; the fluoride joins coolant salts of molten-salt reactors.
Health, safety and environment
Biological role
It has no known biological function and is toxic: inhaled dust causes chronic beryllium disease, an immune lung illness with granulomas.
Safety
Machining, welding or grinding beryllium alloys requires extraction, respirators and medical surveillance. Solid metal in normal use poses very low risk.
Environment
Mine dust and workshop waste are controlled; recycling is limited and residues go to authorized management centers.
Frequently asked questions about Beryllium
Why is beryllium toxic if it is so light and useful?
Because inhaled dust or fumes trigger an immune reaction in sensitized people: granulomas form in the lungs and breathing capacity declines. This chronic beryllium disease does not come from touching solid metal, but from breathing particles when cutting, grinding or welding. Hence strict extraction and respirators in industry.
What is berylliosis?
Chronic beryllium disease is an inflammatory lung illness that can appear in sensitized people after exposure to beryllium dust. The immune system reacts to the metal and forms granulomas in the lungs, causing cough, breathlessness and fatigue. Prevention with ventilation and respiratory protection is essential.
Is beryllium found in household objects?
Pure beryllium is practically absent from ordinary household objects. It can appear in tiny amounts in copper-beryllium alloys used in some electrical contacts, springs or spark-free tools. In normal use the exposure risk is very low because the metal is locked in the alloy; the danger appears when cutting or polishing these materials.
Where is beryllium found in nature?
It appears forming minerals, beryl being the best known. This group includes gems such as emerald and aquamarine, colored by traces of other elements. It is never found free as pure metal. Industrial production starts from bertrandite and beryl, restricted by the health risks of inhaling dust.
Why is beryllium used in alloys?
It is added to alloys, especially copper, to greatly increase hardness, mechanical strength, electrical conductivity and fatigue resistance. Copper-beryllium alloys do not spark on impact with steel, so they are used for tools in explosive atmospheres, electrical contacts, springs and aerospace parts.
Is beryllium lighter than aluminium?
Yes. Beryllium is even lighter than aluminium and has exceptional specific stiffness. This combination suits aerospace parts, satellites, telescope mirrors and X-ray equipment. But it is costlier, more brittle and more toxic to handle, so it never replaces aluminium in everyday uses.
How are exposed workers protected?
Protection rests on keeping beryllium dust out of breathable air: local extraction, wet processes when possible, machine enclosures, controlled cleaning and suitable respirators. Work hygiene, banning eating in the work area and specific medical surveillance are also essential.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.