Beryllium (Be)
Beryllium (Be) is element 4 of the periodic table, an alkaline earth metal in period 2 and group 2. Its standard atomic weight is 9.0121831, so one mole of beryllium atoms has a mass of 9.0121831 g. At room temperature it is a solid; it melts at 1286.85 °C and boils at 2470.85 °C.
| Atomic number | 4 |
|---|---|
| Symbol | Be |
| Standard atomic weight | 9.0121831 |
| Molar mass | 9.0121831 g/mol |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 2 |
| Block | s-block |
| Electron configuration | [He] 2s2 |
| Oxidation states | +2 |
| Electronegativity (Pauling) | 1.57 |
| Atomic radius (van der Waals) | 153 pm |
| First ionisation energy | 9.323 eV (899.5 kJ/mol) |
| Electron affinity | — |
| State at room temperature | Solid |
| Melting point | 1560 K (1286.85 °C) |
| Boiling point | 2744 K (2470.85 °C) |
| Density | 1.85 g/cm³ |
| Discovered | 1798 |
Group 2
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Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.