|Atomic Symbol||Atomic symbol::TI|
|Atomic Number||Atomic number::81|
|Atomic Weight||Atomic weight::204.4 g/mol|
|Chemical series||Poor metal|
|Appearance|| Silver colored, tarnishes to grayish blue|
|Group, Period, Block||IIIA, 6, 5p|
|Electron configuration||[Xe] 4f14, 5d10, 6s2, 6p1|
|Electrons per shell|| 2,8,18,32,18,3 |
|CAS number||CAS number::7440-28-0|
|Melting point||Melting point::304 °C|
|Boiling point||Boiling point::1473 °C|
|Isotopes of Thallium|
|All properties are for STP unless otherwise stated.|
Thallium is a chemical element classified as a poor metal in the periodic table of elements. Its name is derived from the Greek word 'thallos' which means a green light or branch, this name was chosen because of the green spectral emissions lines. Thallium was discovered by Sir William Crookes in 1816 after his father left him a small fortune. Crookes also invented the cathode ray. Doctors, chemists and many other manufactures have found uses for Thallium, though always in small doses. Thallium is often referred to as The Poisoner's Poison because of its immediate toxic effects.
Metals are often thought of as strong and unbreakable, however Thallium is a soft, flexible metal and can even be cut with a knife. Thallium not yet exposed to oxygen is silver colored, but oxygen transforms its appearance into a blue-gray color. Thallium dissolves completely in nitric acid and sulfuric acid. Thallium is not only odorless, but tasteless as well. Thallium reacts with both oxygen and various acids. Thallium oxide occurs immediately when it is exposed to oxygen, making only an outer thin layer easy to peel off.
Thallium rarely occurs in the earth crust, Chemists assume it appears 0.7 parts per one million, making it one of the least abundant elements. Crookesite, lorandite, and hutchinsonite are minerals that often contain Thallium. Most of the Thallium found in commercial products is small amounts within Zinc, Copper and Lead. The spread of Thallium is done throughout moist soil and sludge. Modules of Manganese also contain Thallium, but being found on the ocean floor it is expensive to extract. Thallium minerals are often found as well, but no commercial use has been found yet. When pyrite ore is roasted, the amount of Thallium becomes apparent as a sulfuric acid by-product. 
Thallium was the key ingredient in many rodent as well as ant killers for many years, until it was discovered to be used by housewives to kill their husbands. Chemists use it in selenium rectifiers, detecting gamma radiation, and detecting infrared radiation. Thallium is useful also in low melting glass. Thallium can be purchased at $40 per pound. Thallium is used in hospitals for heart tests, determining how healthy and ready for activity a heart is, as well as testing if coronary artery blockage is present. Thallium becomes present under a gamma camera and allows doctors to study ones heart muscles after extreme exercise. Thallium stress tests are also known as Myocardial Perfusion Imaging (MPI), Multigated Acquisition (MUGA) Scan, and Radionuclide Stress Test and Nuclear Stress Test.  Doctors have also found Thallium to be useful for treating skin problems and ringworm, but it is a controversial medicine because of how a slight overdose may become deadly so quick. Thallium has also been found in cigarette smoke. The United States banned the use of Thallium as a rodent killer in 1975 because of discovered links between it and child accidental deaths. When mercury is needed for a project, but must be put at a temperature below -40 degrees Celcius a Mercury-Thallium alloy will be used, allowing the element to drop an additional 20 degrees before freezing. Thallium sulphide conducts electricity in a way that changes exposure to infrared lights, making it a useful tool in the process of creating photocells. 
English Chemist and physicist, Sir William Crookes, was searching for traces of tellurium in a plant sample; instead of finding the yellow traces of tellurium he discovered a bright green strip. After further study he revealed this light was thallium, and in 1861 this element was named and added to the rest of known elements. In the same year Claude August Lamy also made the discovery of Thallium but Crookes, having no relation to Lamy, had already published his findings.  A year later Thallium was shown at a conference in London. When first grouped thallium was placed in the sulfur family, but quickly moved to IIIA when its similarities to lead and mercury were realized. From 1861 to 1869 Crookes conducted numerous experiments on the element he discovered. Weighing it in a vacuum the discovery that Thallium was heavier cold than when hot was made. 
Thallium as a Poison
In 2006 a Russian spy named Alexander Litvinenko was poisoned with Thallium when drinking tea with an old friend from the KGB. A small dose of this extremely dangerous element gives the taker symptoms mirroring that of food poison, which may often slow the discovery of the presence of Thallium, because the drug is often placed in food. If ignored, Thallium causes it's victim to have severe muscle problems, headaches, convulsions, even spiraling into comas, dementia or even stages of psychotic behavior. Litvineko's case took 15 days to discover the Thallium, he had already lost all energy, muscle control and all of his hair. The poison had attacked many of his white blood cells, giving him only a 50-50 percent chance of surviving against infection. The antidote of Thallium, Prussian Blue, was used but being two weeks into the poisoning it was not fully effective, prussian Blue must be administered within six hours. The attack of Thallium against Alexander displays the expecting results of Thallium poison in and adult human. Litvineko was required to endure muscle rebuilding therapy, physiotherapy, as well as a possible bone marrow transport surgery. He died on 23 November at the age of 43 as result of the attack. Many other famous cases of Thallium poisoning, or suspected poisoning, have occurred recently; it is rumored that a plot against Nelson Mandela was issued by South African agents by use of Thallium. A pharmacist by the name of Agatha Christie used Thallium to kill characters in her novel, A Pale Horse. Countless cases from China to Russia have appeared with Thallium as the attempted killer, being used by spies to even school girls. 
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