do you know what is its symbol?
TI .
Thallium
. Tl and Tl are the only stable isotopes and make up nearly all of natural thallium. Tl is the most stable radioisotope, with a half-life of 3.78 years. It is made by the neutron activation of stable thallium in a nuclear reactor. The most useful radioisotope, Tl (half-life 73 hours), decays by electron capture, emitting X-rays (~70–80 keV), 
what is thallium? A chemical element. what are its characteristics? A thallium atom has 81 electrons arranged in the configuration [Xe]4f5d6s6p. It is malleable and sectile enough o be cut with a knife at room temperature. It has a metallic luster. how many isotopes does it have? 41. how is it produced? It is obtained as a by-product of smelting of copper, zinc, and lead ores. is it used in medicines? It is used for stress tests for risk stratification in patients with coronary artery disease. what are the symptoms of the disease that you just mentioned? Angina, shortness of breath, sweating , nausea or vomiting and lightheadedness. can the element you mentioned before be used in electronics? Yes, it is used in photoresistors. what are these? A passive component that decreases resistance with respect to receiving luminosity on the component's sensitive surface.. is the element you mentioned before toxic? Yes, and in cases fatal. has anybody ever died from it? Yes. can you please name some compounds that it is part of? Organothallium compounds like trimethylthallium and triethylthallium. how does it occur in nature? In nature it is mostly found with potassium-based minerals in clays, soils, and granites. how does it occur in nature? In nature it is mostly found with potassium-based minerals in clays, soils, and granites.
wiki:19618767
Thallium [SEP] Isotopes
Thallium has 41 isotopes which have atomic masses that range from 176 to 216. Tl and Tl are the only stable isotopes and make up nearly all of natural thallium. Tl is the most stable radioisotope, with a half-life of 3.78 years. It is made by the neutron activation of stable thallium in a nuclear reactor. The most useful radioisotope, Tl (half-life 73 hours), decays by electron capture, emitting X-rays (~70–80 keV), and photons of 135 and 167 keV in 10% total abundance; therefore, it has good imaging characteristics without excessive patient radiation dose. It is the most popular isotope used for thallium nuclear cardiac stress tests.