Write about Tungsten atom.

     

Tungsten or Wolfram is a chemical element, with the symbol W and atomic number 74.  Tungsten is a rare metal found natrually on Earth almost exclusively combined with other elements in chemical compounds.  It was identified as a new element in 1781 and first isolated as a metal in 1783.  It important ores include scheelite, and wolframite, lending the element its alternate name.  

     The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements discovered, melting at 3,422 C its density is 19.25 grams per cubic centimetre, comparable with that of uranium and gold, and much higher than that of lead.  Polycrystalline tungsten is an intrinsically brittle and hard material making it difficult to work.  However, pure single-crystalline tungsten is more ductile and can be cut  with a hard-steel hacksaw.

     Tungsten is the only metal in the third tranition series that is known to occur in biomolecules, being found in a few species of bacteria and archaea.   However, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to more familiar forms of animals life.