Beryllium (Be)
Beryllium is element 4, a alkaline earth metal in period 2, group 2 of the periodic table. At room temperature it is a solid.
Electron configuration [He] 2s2
Electrons per shell 2, 2
Beryllium data
| Atomic number | 4 |
|---|---|
| Symbol | Be |
| Atomic mass | 9.012 u |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 2 |
| Block | s |
| State at 25 °C | solid |
| Melting point | 1560 K (1286.9 °C) |
| Boiling point | 2743 K (2469.9 °C) |
| Density | 1.848 g/cm³ |
| Electronegativity (Pauling) | 1.57 |
| Atomic radius | 90 pm |
| 1st ionization energy | 900 kJ/mol |
| Electron affinity | 0 kJ/mol |
| Oxidation states | +2 |
| Common ion charge | 2+ |
| Discovered | 1798 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through beryllium’s configuration and its ions →
Where beryllium sits
Beryllium belongs to the alkaline earth metals. Its Pauling electronegativity of 1.57 is mid-range; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Beryllium FAQ
What is the electron configuration of beryllium?
Beryllium (Z = 4) has the configuration 1s2 2s2. In noble-gas shorthand that is [He] 2s2.
How many valence electrons does beryllium have?
2 (outer shell (n = 2)).
What is the atomic mass of beryllium?
The standard atomic weight of beryllium is 9.012 u, so one mole weighs 9.012 g.
Is beryllium a metal?
Yes. Beryllium is a alkaline earth metal.
What is the charge of a beryllium ion?
Beryllium most commonly forms Be2+.