Thallium (Tl): Properties, Uses and Facts in 3D
Thallium is element 81 on the periodic table, a post-transition metal. At room temperature it is a solid. Open it in the 3D Periodic Table to spin its tile, see its electron shells and read its story.
Explore in 3DThallium quick facts
| Atomic number | 81 |
|---|---|
| Symbol | Tl |
| Atomic mass | 204.383 |
| Category | Post-Transition Metal |
| Group and period | Group 13, period 6 |
| Block | p-block |
| State at room temperature | Solid |
| Electron configuration | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹ |
| Electrons per shell | 2, 8, 18, 32, 18, 3 |
| Discovered | 1861, Crookes |
What is thallium used for?
- Thallium-201 cardiac imaging
- Infra-red optics
- Rodenticide (historical. Now banned)
Interesting facts about thallium
- Agatha Christie, a former hospital dispensary worker, used thallium poisoning in The Pale Horse
- Thallium was once used as a rat poison and depilatory (hair remover) before its toxicity was understood
- Named from Greek "thallos" meaning green twig. From its vivid green spectral lines
Thallium was discovered in 1861 by Crookes in Britain.
Where thallium sits on the periodic table
Thallium is in group 13, period 6. Tap any element to open its page.
Other post-transition metals
Thallium questions
What is the atomic number of thallium?
Thallium has atomic number 81, so every thallium atom has 81 protons in its nucleus. Its symbol is Tl and its atomic mass is 204.383.
Is thallium a metal?
Thallium is a metal. On the periodic table it is grouped as a post-transition metal, found in group 13, period 6.
What is the electron configuration of thallium?
The electron configuration of thallium is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹. Its electrons sit in 6 shells: 2, 8, 18, 32, 18, 3.
What is thallium used for?
Thallium is used for thallium-201 cardiac imaging, infra-red optics and rodenticide (historical. now banned).
Who discovered thallium?
Thallium was discovered in 1861 by Crookes in Britain.
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