Beryllium (Be): Electron Configuration, Properties and Uses
Beryllium (Be): Electron Configuration, Properties and Uses
Electron configuration [He] 2s2 · group 2 · period 2 · Ar 9.0122
Beryllium data
- Atomic number
- 4
- Relative atomic mass
- 9.0122
- Group
- 2
- Period
- 2
- Block
- s
- Category
- Alkaline earth metal
- Electron configuration
- [He] 2s2
- Full configuration
- 1s2 2s2
- Electrons per shell
- 2, 2 (K L)
- Valence electrons
- 2
- Electronegativity (Pauling)
- 1.57
- First ionisation energy
- 9.323 eV
- Atomic radius (van der Waals)
- 153 pm
- State at room temperature
- Solid
- Melting point
- 1287 °C
- Boiling point
- 2471 °C
- Density
- 1.85 g/cm³
- Common oxidation states
- +2
- Discovered
- 1798
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 2
Orbital diagram (outer electrons)
About beryllium
With atomic number 4, beryllium (Be) has 4 protons in its nucleus and 4 electrons as a neutral atom. It is an alkaline earth metal in group 2, period 2, s-block. Beryllium was first discovered in 1798. Beryllium is a solid at room temperature, melting at 1287 °C and boiling at 2471 °C.
Beryllium electron configuration
The electron configuration of beryllium is 1s2 2s2, or in short [He] 2s2. Its electrons occupy 2 shells: K = 2, L = 2. Beryllium has 2 valence electrons in the L shell (2s2), which is why it sits in group 2. When it forms cations, electrons leave the outermost subshell first: Be2+ = [He] (like helium).
Filling order: 1s2(2) → 2s2(4)
Uses of beryllium
In industry and the laboratory, beryllium turns up in many places, for example copper-beryllium alloys for springs and non-sparking tools, X-ray tube windows and space telescope mirrors.
Safety
Beryllium dust and compounds are very hazardous to inhale; they cause chronic lung disease and are carcinogenic. Always read the safety data sheet (SDS) before working with a chemical.
Other elements in group 2
Frequently asked questions
What is the electron configuration of beryllium?
The electron configuration of beryllium (Be, atomic number 4) is 1s2 2s2, or [He] 2s2 in short. By shell: 2, 2.
How many valence electrons does beryllium have?
Beryllium has 2 valence electrons.
Which group and period is beryllium in?
Beryllium is in group 2, period 2, s-block.
What is the atomic mass of beryllium?
The relative atomic mass of beryllium is 9.0122. Use it to calculate molar mass with the molar mass calculator.
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