write about Thallium atom.

     

Thallium 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 thallium independently in 1861, i residues of sulfuric acid production.  Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line.  Thallium, form Greek meaning "green shoot" or "twig", was named by Crookes. 

     It was isolated by both Lamy and Crookes in 1862; Lamy by electrolysis, and crookes by precipitation and melting of the resultant powder.  Crookes exhibited it as a powder precipitated by zinc at the international exhibition, which opened on 1 May that year.

     Thallium tends to form the +3 and +1 oxidation states.  The +3 state resembles that of the other elements in group 13 (boron, aluminium, gallium, indium).  However, the +1 state, which is far more prominent in thallium than the elements above metals, and thallium (I) ions are found geologically mostly in potassium bases ores, and are handled in many ways like potassium ion(K+) by ion pumps in living cells.  

     Soluble thallium salts are highly toxic, and they were historically used in rat poisons and insecticides.  Use of these compounds has been restricted or banned in many countries, because of their nonselective toxicity.  Thallium poisoning usually results in hair loss, although this characteristic symprom does not always surface.  Because of its historic popularity as a murder weapon, thallium has gained notoriety as "the poisoner's poison" and "inheritance powder".