Zn Keyring 20x30 mm.

<div>   </div> <div> <strong> Atomic number       <span class = "Apple-tab-span" style = "white-space: pre;"> </span>30</strong></div> <div> <strong> Atomic mass         <span class = "Apple-tab-span" style = "white-space: pre;"> </span>65,39</strong></div> <div> <strong> Density, kg / m?       <span class = "Apple-tab-span" style = "white-space: pre;"> </span>7140</strong></div> <div> <strong> Temperature </strong> </div> <div> <strong> melting, ° С         <span class = "Apple-tab-span" style = "white-space: pre;"> </span>419,5</strong></div> <div>   </div> <div > Zinc is a brittle, bluish-white transition metal. An alloy of zinc and copper - brass - was known to the ancient Greeks and Egyptians. It was not possible to isolate pure zinc for a long time. In 1746 A.S. Marggraf developed a method for producing metal by calcining a mixture of its oxide with coal without access to air in clay refractory retorts, followed by condensation of zinc vapor in refrigerators. Zinc smelting began on an industrial scale in the 17th century. & Nbsp; </div> <div> Pure metallic zinc is used to recover precious metals extracted by underground leaching (gold, silver). In addition, zinc is used to extract silver, gold (and other metals) from crude lead in the form of zinc intermetallic compounds with silver and gold, which are then processed by conventional refining methods. It is used to protect steel from corrosion (galvanizing surfaces that are not subject to mechanical stress, or metallization - for bridges, tanks, metal structures). </div> <div>   </div>