History
         Thallium was found by an English chemist, Sir William Crookes. He discovered it spectroscopically in 1861 and named after a the identifier of thallium, a green spectral line. Crookes and Claude-Auguste Larny both isolated the metal in 1862, separately.

Properties
         Thallium is soft, malleable and can be cut with a knife. If thallium is left exposed to air, a heavy oxide will build up. When put in water it bonds with hydrogen. 25 are isotopic which means that they all have the same amount of protons and electrons but different amounts of neutrons. When in nature they are two combined isotopes. It is odorless and tasteless.

Uses
         Although thallium was used as a rodenticide and ant killer, it has been illegal in US households since 1975 because it is poisonous. It is illegal in some other countries as well. It is also used in photo cells because of how it conducts electricity when exposed to infrared light. It is used for some glasses that have a high index of refraction and also is used as nuclear medicine and to cure ringworm. It is also used for thermometers that are needed in extremely cold temperatures. It lowers the freezing point 20°.

Sources
         Thallium is found 10 times more than silver. About 30 tons are produced every year. It is very good at transporting because it is water soluble and spreads easily with groundwater. Thallium is found in potassium, sylvite and pollucite. Two of the few thallium minerals known are crookesirte and lorandite.

Health Effects
         Some radioactive thallium compounds are used for cardiovascular imaging to detect heart disease.

Health Issues
         Although rat poison with thallium in it is useful, if we accidentally get some in our body, it can cause stomachaches, a damaged nervous system,  or even death. The damage it causes to the nervous system may leave a person with trembling, paralyses or change in behavior. If a pregnant woman gets thallium poisoning it often causes congenital disorders. Tiredness, headaches, depressions, lack of appetite, leg pains, hair loss and sight issues may result if thallium builds up in a person’s body. If food has thallium in it and it is eaten it could cause nerve pains and joint pains. 15-20 mg/kg of thallium is definitely lethal to humans and an amount as low as 8 mg/kg can be. The most survived by anyone (with treatments) was 28 mg/kg.