Name the scientist who invented the current method
of choosing Chemical symbols?
Answers
Explanation:
The development of the modern scientific method was slow and arduous, but an early scientific method for chemistry began emerging among early Muslim chemists, beginning with the 9th-century chemist Jābir ibn Hayyān (known as "Geber" in Europe), who is sometimes regarded as "the father of chemistry".
Answer:
Thallium (Tl), chemical element, metal of main Group 13 (IIIa, or boron group) of the periodic table, poisonous and of limited commercial value. Like lead, thallium is a soft, low-melting element of low tensile strength. Freshly cut thallium has a metallic lustre that dulls to bluish gray upon exposure to air. The metal continues to oxidize upon prolonged contact with air, generating a heavy nonprotective oxide crust. Thallium dissolves slowly in hydrochloric acid and dilute sulfuric acid and rapidly in nitric acid.
Rarer than tin, thallium is concentrated in only a few minerals that have no commercial value. Trace amounts of thallium are present in sulfide ores of zinc and lead; in the roasting of these ores, the thallium becomes concentrated in the flue dusts, from which it is recovered.
British chemist Sir William Crookes discovered (1861) thallium by observing the prominent green spectral line generated by selenium-bearing pyrites that had been used in the manufacture of sulfuric acid. Crookes and French chemist Claude-Auguste Lamy independently isolated (1862) thallium, showing it to be a metal.
Two crystalline forms of the element are known: close-packed hexagonal below about 230 °C (450 °F) and body-centred cubic above. Natural thallium, the heaviest of the boron group elements, consists almost entirely of a mixture of two stable isotopes: thallium-203 (29.5 percent) and thallium-205 (70.5 percent). Traces of several short-lived isotopes occur as decay products in the three natural radioactive disintegration series: thallium-206 and thallium-210 (uranium series), thallium-208 (thorium series), and thallium-207 (actinium series).
Thallium metal has no commercial use, and thallium compounds have no major commercial application, since thallous sulfate was largely replaced in the 1960s as a rodenticide and insecticide. Thallous compounds have a few limited uses. For example, mixed bromide-iodide crystals (TlBr and TlI) that transmit infrared light have been fabricated into lenses, windows, and prisms for infrared optical systems. The sulfide (Tl2S) has been employed as the essential component in a highly sensitive photoelectric cell and the oxysulfide in an infrared-sensitive photocell (thallofide cell). Thallium forms its oxides in two different oxidation states, +1 (Tl2O) and +3 (Tl2O3). Tl2O has been used as an ingredient in highly refractive optical glasses and as a colouring agent in artificial gems; Tl2O3 is an n-type semiconductor. Alkali halide crystals, such as sodium iodide, have been doped or activated by thallium compounds to produce inorganic phosphors for use in scintillation counters to detect radiation.