Selenium (Se) — Element 34: Properties & Data | Aladdin Scientific
Selenium(Se) — Element 34
Selenium (Se) is a nonmetal with atomic number 34 and atomic mass 78.97. It has melting point 493.65 K (220 °C), boiling point 958 K (685 °C), density 4.809 g/cm³. It sits in group 16 and period 4 of the periodic table and was discovered in 1817.
Key facts
| Atomic mass | 78.9700 u |
|---|---|
| Electron configuration | [Ar]4s2 3d10 4p4 |
| Oxidation states | +6, +4, -2 |
| Electronegativity (Pauling) | 2.55 |
| Atomic radius (van der Waals) | 190 pm |
| Ionization energy | 9.752 eV |
| Electron affinity | 2.021 eV |
| Melting point | 493.65 K |
| Boiling point | 958 K |
| Density | 4.809 g/cm³ |
| Standard state | Solid |
| Year discovered | 1817 |
Frequently asked questions
What is the electron configuration of selenium?
The ground-state electron configuration of selenium is [Ar]4s2 3d10 4p4.
What group and period is selenium in?
Selenium (Se) is in group 16 and period 4 of the periodic table, classified as a nonmetal.
What is the melting point of selenium?
Selenium melts at 493.65 K (220 °C).
What is the standard state of selenium?
Selenium is a solid at standard temperature and pressure.
Related elements
About this data: property values compiled from IUPAC Standard Atomic Weights (2021), the NIST Atomic Spectra Database, and PubChem. Curated by the Aladdin Scientific technical team. Last reviewed: .