Quick answerSelenium (Se) is a nonmetal with atomic number 34 and an atomic mass of 78.971 (2023), in group 16, period 4. It was discovered by Jöns Jacob Berzelius in 1817. It is used for solar cells and photocopiers. Its electron configuration is [Ar] 3d10 4s2 4p4.
Selenium is a light-sensitive element that once ran photocopiers and solar cells, and it still guards shampoos and glass against flaws.
Key facts
| Symbol | Se |
|---|---|
| Atomic number | 34 |
| Atomic mass | 78.971 (IUPAC standard atomic weight, 2023) |
| Category | nonmetal |
| Group | 16 |
| Period | 4 |
| Block | p-block |
| Electron configuration | [Ar] 3d10 4s2 4p4 |
| Discovered | Jöns Jacob Berzelius, 1817 |
| Uses | solar cells, photocopiers, anti-dandruff shampoo, glass decolourising, dietary supplements |
Quick quiz
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Keep exploring
- Periodic table — all 118 elements
- Hydrogen (H) — another nonmetal, atomic number 1
- Carbon (C) — another nonmetal, atomic number 6
- Nitrogen (N) — another nonmetal, atomic number 7
- Oxygen (O) — another nonmetal, atomic number 8
- Phosphorus (P) — another nonmetal, atomic number 15
- Sulfur (S) — another nonmetal, atomic number 16
Sources & last updated
- CIAAW — Standard Atomic Weights
- PubChem Periodic Table
- Wikipedia — Timeline of chemical element discoveries
Last updated: . Figures are shown with their year; where sources disagree, the value is left out rather than estimated.