Element Thallium
It is a chemical element with the symbol Tl and atomic number 81.
It is a gray post-transition metal that is not found free in nature.
When isolated, thallium resembles tin, but discolors when exposed to air.
Chemists William Crookes and Claude-Auguste Lamy discovered Element Thallium independently in 1861, in residues of sulfuric acid production.
Names and Identifiers
| Chemical Formula: | TI |
| CAS: | 7440-28-0 |
| Molecular Weight: | 204.38300 g/mol |
| EC Number : | 231-138-1 |
| MDL Number: | MFCD00134063 |
| Color: | silvery-gray |
| Other Names: | n/a |
| PubChem CID: | 5359464 |
| IUPAC Name: | Thallium |
| Inchl: | InChI=1S/TI |
| InChI Key: | BKVIYDNLLOSFOA-UHFFFAOYSA-N |
| Canonical SMILES: | [TI] |
| ICSC Number: | 0077 |
Physical & Chemical Properties
| Phase: | Solid |
| Density: | 11.85 g/cm3 |
| Boiling Point: | 1746 K (1473 °C, 2683 °F) |
| Melting Point: | 577 K (304 °C, 579 °F) |
| Molecular Formula: | TI |
| Flash Point: | n/a |
| Exact Mass: | 204.97400 |
| Symbol: |   |
| Signal Word: | Danger |
| Hazard Statements: | H300 + H330-H373-H413 |
| Precautionary Statements: | P260-P264-P284-P301 + P310-P310 |
| Hazard Codes: | Xn,T+ |
| Risk Phrases: | 26/28-33-53-36/37/38-20/22-36/38 |
| Safety Phrases: | S13-S28-S45-S61-S36/37/39-S36/37-S26 |
| RIDADR: | UN 3288 6.1/PG 2 |
| WGK Germany: | 3 |
| RTECS: | XG3425000 |
| Packaging Group: | II |
| Hazard Class: | 6.1 |
Thallium has 25 isotopes which have atomic masses that range from 184 to 210.
Naturally occurring isotopes
| Isotope | Mass/Da | Natural abundance (atom %) | Nuclear spin (I) | Magnetic moment (μ/μN) |
|---|---|---|---|---|
| 203Tl | 202.972320 (5) | 29.524 (14) | 1/2 | 1.622257 |
| 205Tl | 204.974401 (5) | 70.476 (14) | 1/2 | 1.6382135 |
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 200Tl | 199.97095 | 1.087 d | EC to 200Hg | 2 | 0.04 |
| 201Tl | 200.97078 | 3.040 d | EC to 201Hg | 1/2 | 1.605 |
| 202Tl | 201.97209 | 12.23 d | EC to 202Hg | 2 | 0.06 |
| 204Tl | 203.97385 | 3.78 y | EC to 204Hg; β– to 204Pb | 2 | 0.09 |