描述
Thallium, also known as 81tl or talio, is a member of the class of compounds known as homogeneous post-transition metal compounds. Homogeneous post-transition metal compounds are inorganic compounds containing only metal atoms,with the largest atom being a post-transition metal atom. Thallium can be found in a number of food items such as turnip, romaine lettuce, red beetroot, and sunburst squash (pattypan squash), which makes thallium a potential biomarker for the consumption of these food products. Thallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal 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, in residues of sulfuric acid production. Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line. Thallium, from Greek θαλλός, thallós, meaning "a 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 .