![[ATOM]](atom.gif) |
Thallium
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Information valid for Tl-204 unless otherwise noted
Basic Information
Symbol: Tl
Atomic Number: 81
Mass: 204.3833
Melting Point: 303.5 C
Boiling Point: 1457.0 C
Number of Protons/Electrons: 81
Number of Neutrons: 123
Classification: Other Metals
Crystal Structure: Hexagonal
Density @ 293 K: 11.85 g/cm3
Color: bluish
Atomic Structure
![[Bohr Model of Thallium]](b0081.gif) |
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Number of Energy Levels: 6
First Energy Level: 2
Second Energy Level: 8
Third Energy Level: 18
Fourth Energy Level: 32
Fifth Energy Level: 18
Sixth Energy Level: 3
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Isotopes
| Isotope |
Half Life |
| Tl-200 |
1.08 days |
| Tl-201 |
3.03 days |
| Tl-202 |
12.23 days |
| Tl-203 |
Stable |
| Tl-204 |
3.78 years |
| Tl-205 |
Stable |
| Tl-206 |
4.2 minutes |
| Tl-207 |
4.77 minutes |
| Tl-208 |
3.05 minutes |
| Tl-209 |
2.2 minutes |
| Tl-210 |
1.3 minutes |
Facts
Date of Discovery: 1861
Discoverer: Sir William Crookes
Name Origin: From the Greek word thallos (young shoot)
Uses: rat and ant poisons, detecting infrared radiation
Obtained From: crookesite, hutchinsonite, lorandite