Selenium (Se) — Reactive nonmetal. Atomic number 34.
Gray or red solid
- Atomic number: 34
- Symbol: Se
- Atomic mass: 78.971 u
- Category: Reactive nonmetal
- State: Solid
- Melting point: 220.85 °C / 494 K
- Boiling point: 684.85 °C / 958 K
- Density: 4.81 g/cm³ (20°C)
- Electron configuration: [Ar] 3d10 4s2 4p4
- Oxidation states: −2, +4, +6
- Electronegativity: 2.55
- Discovered by: Jöns Jacob Berzelius (1817)
Common uses: Glass production, Solar cells, Pigments, Electronics
Biological role: Essential trace nutrient.
Frequently Asked Questions about Selenium
What is the atomic number of selenium?
Selenium has an atomic number of 34, meaning each atom contains 34 protons in its nucleus.
What is the atomic mass of selenium?
The standard atomic weight of selenium is 78.971 u (unified atomic mass units).
What category does selenium belong to?
Selenium is classified as a reactive nonmetal.
What is the state of selenium at room temperature?
Selenium is a solid at 20 °C (68 °F).
What is the melting point of selenium?
The melting point of selenium is 220.85 °C / 494 K.
What is the boiling point of selenium?
The boiling point of selenium is 684.85 °C / 958 K.
What is the density of selenium?
The density of selenium is 4.81 g/cm³ (20°C).
What is the electronegativity of selenium?
Selenium has a Pauling electronegativity of 2.55.
What is the electron configuration of selenium?
The electron configuration of selenium is [Ar] 3d10 4s2 4p4.
What are the common oxidation states of selenium?
Selenium commonly exhibits the following oxidation states: −2, +4, +6.
When was selenium discovered?
Selenium was discovered in 1817 by Jöns Jacob Berzelius.
Is selenium radioactive?
Selenium is a stable element with no naturally occurring radioactive isotopes.
What is the biological role of selenium?
Essential trace nutrient.
What are the common uses of selenium?
Selenium is used for: Glass production; Solar cells; Pigments; Electronics.
