81Tl204.38
Thallium
Post-transition metalsSofter metals with lower melting points, often used in alloys and solders.
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹
- Atomic number
- 81
- Atomic mass
- 204.38
- Protons
- 81
- Neutrons
- 123 (most common)
- Electrons
- 81
- Shells
- 2, 8, 18, 32, 18, 3
- State at 25 °C
- Solid
- Position
- Group 13, period 6
Proton (+)Neutron (0)Electron (−)
Discovered byWilliam Crookes, 1861William Crookes: 1 element
Crookes spotted a bright green line in his spectroscope. The name comes from the Greek thallos, meaning green shoot.
Did you know?
- It is highly toxic.
- It was once used as rat poison, which is now banned in many countries.
Where it's found
- Traces in zinc and lead ores
What it's used for
- Infrared optics
- Some electronics
Try it
There's no safe home experiment for Thallium. Explore it with the animated atom above instead.