Quick answerAstatine (At) is a halogen with atomic number 85 and a mass number of 210 (the most stable isotope), in group 17, period 6. It was discovered by Corson, MacKenzie, and Segrè in 1940. It is used for cancer research and thyroid studies. Its electron configuration is [Xe] 4f14 5d10 6s2 6p5.
Astatine is the rarest natural element on Earth, less than a gram exists in the crust at any moment, and doctors are testing it against cancer.
Key facts
| Symbol | At |
|---|---|
| Atomic number | 85 |
| Atomic mass | [210] — mass number of the most stable isotope |
| Category | halogen |
| Group | 17 |
| Period | 6 |
| Block | p-block |
| Electron configuration | [Xe] 4f14 5d10 6s2 6p5 |
| Discovered | Corson, MacKenzie, and Segrè, 1940 |
| Uses | cancer research, thyroid studies, nuclear medicine research, radiotracer studies |
Quick quiz
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Keep exploring
- Periodic table — all 118 elements
- Fluorine (F) — another halogen, atomic number 9
- Chlorine (Cl) — another halogen, atomic number 17
- Bromine (Br) — another halogen, atomic number 35
- Iodine (I) — another halogen, atomic number 53
- Tennessine (Ts) — another halogen, atomic number 117
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.