Periodic Table -> Thallium


Thallium Details

Thallium Symbol: Tl

Thallium Atomic Number: 81

Thallium Atomic Weight: 204.3833

What is Thallium?

Thallium (atomic number 81, symbol TI) is a post-transition metal and chemical element that was discovered in 1861 by Claude-Auguste Lamy and William Crookes. They discovered the element independently by using a new method known as flame spectroscopy. This is a method used to study the composition of chemicals and minerals.

Chemical and Physical Properties
Thallium is a lustrous, sectile, malleable, and soft metal that tarnishes when reacting with air. Nitrate and sulfate salts are formed when thallium reacts with nitric acid and sulfuric acid. The element has 25 isotopes and TI-205 and TI-203 are stable. This metal has a hexagonal close-packed structure, and the common oxidation states are 1, 2, and 3.

Applications and Occurrence
Thallium is found in different ores, including metal-sulfide ores, zinc, lead, and copper. It occurs in minerals found in granites, soils, and clays. Minerals that contain silver, lead, copper, arsenic, and antimony also contain thallium in selenides and sulfides. There are some thallium minerals as well, including lorandite and crookesite. Other minerals include sabatierite, routhierite, hutchinsonite, and gabrielite, the latter of which is found in Switzerland. Minerals such as christite and bukovite also contain thallium. Christite is found in deposits in Nevada, the US, and China while bukovite occurs in deposits in Argentina, France, Sweden, and the Czech Republic.

The element is used in glass production and the pharmaceutical industry. It is also used to produce superconductors, photoresistors, and glasses. High-density glasses are produced from thallium, arsenic, selenium, and sulfur. Radioactive isotopes have applications in nuclear medicine, especially nuclear cardiography. Its compounds and salts are used to make metal halide lamps and solutions and in gold plating.
Thallium sulphate is used to make rat poison. It is a reagent for research purposes. The element is also used to manufacture thermometers, photocells, and reflective lenses. Pesticides that contain thallium sulphate are banned in the developed countries but still used in some developing countries. The reaction of sulfuric acid and thallium produces sulphate.

Health Hazards and Effects on the Environment
Thallium is a very poisonous metal and poisoning can occur. The symptoms include severe pain, hair loss, red skin, and brain damage. Exposure occurs through inhalation, touching, and living close to waste sites where thallium is found in higher concentrations. Exposure may result in birth defects and side effects such as temporary hair loss, diarrhea, and vomiting. Thallium also affects major organs such as the kidneys, liver, heart, and lungs. Higher concentrations can cause death. The effects of prolonged exposure are unknown. Accumulation may result in sight disturbances, leg pain, l?ck of appetite, depression, headache, and tiredness. Nerve and joint pain have been reported as well. Prussian blue is used to treat the symptoms, absorb thallium, and remove it from the body. The carcinogenic effects of thallium have not been studied. Some mammals are also affected, and thallium has toxic effects on plants. The main sources of pollution include metal sewers, coal-burning plants, cement factories, and others.

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