Beryllium (Be) – element 4
Beryllium is a chemical element with the symbol Be and atomic number 4. It is a alkaline earth metal in group 2 (alkaline earth metals), period 2 of the periodic table (s-block), and is a solid at room temperature.
Beryllium (Be) has atomic number 4, atomic mass 9.0122 u and electron configuration [He] 2s2.
Beryllium facts
| Symbol | Be |
|---|---|
| Atomic number | 4 |
| Atomic mass | 9.0122 u (g/mol) |
| Category | alkaline earth metal |
| Group | group 2 (alkaline earth metals) |
| Period | 2 |
| Block | s-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 |
| Noble-gas notation | [He] 2s2 |
| Electrons per shell | 2, 2 |
| Valence electrons | 2 |
Bohr model and shells
Beryllium has 4 electrons in 2 shells: 2, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 1560 K (1286.8 °C) |
|---|---|
| Boiling point | 2742 K (2468.8 °C) |
| Density | 1.85 g/cm³ |
| Electronegativity (Pauling) | 1.57 |
| Electron affinity | -48 kJ/mol |
| Ionization energies | 899.5, 1757.1, 14848.7 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 16.443 J/(mol·K) |
| Discovered by | Louis Nicolas Vauquelin |
Use the atomic mass in the molar mass calculator for any formula containing Be.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of beryllium?
The atomic mass of beryllium is 9.0122 u, so one mole of beryllium atoms weighs 9.0122 g.
What is the electron configuration of beryllium?
Beryllium has 4 electrons: 1s² 2s², or [He] 2s² in noble-gas notation. Electrons per shell: 2, 2.
How many valence electrons does beryllium have?
Beryllium has 2 valence electrons (group 2).
Is beryllium a metal?
Yes. Beryllium is a alkaline earth metal.
Where is beryllium on the periodic table?
Beryllium is in group 2 (alkaline earth metals), period 2, in the s-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.