Element: Beryllium
General data
| Element name | Beryllium |
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| Chemical symbol | Be |
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| Atomic number Z | 4 |
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| Year discovered | 1798 |
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| Standard state (25°C) | Solid |
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| Category | Alkaline earth metal |
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| Block | s |
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| Atomic mass | 9.0122 |
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| CPK color | #C2FF00 |
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Physical properties
| Melting point | 1560 K (1287 °C) |
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| Boiling point | 2744 K (2471 °C) |
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| Density | 1.85 g/cm³ |
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Energy properties
| First ionization energy | 9.323 eV |
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| Electron affinity | no data |
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Atomic structure
| Protons | 4 (Atomic number) |
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| Neutrons (Be-9, most abundant isotope) | 5 |
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| Electrons | 4 |
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| Electron configuration | [He] 2s² |
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| Oxidation states | +2 |
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| Electronegativity (Pauling) | 1.57 |
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| Atomic radius (van der Waals) | 153 pm |
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Ionization energies - NIST ASD (4 states)
Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.
