Zinc

zinc cinc

Zinc (or zinc) was used in India and China hundreds of years before the German chemist Andreas Marggraf identified it as a new element in the 18th century. This element is a rare transition metal that is never found in a pure state in nature, but is present in many minerals. The sphalerite mineral, which contains zinc sulfide, ZnS, is the main source of pure zinc. Another major mineral, hemimorphite, contains zinc and silicon. Zinc is essential in our diet. We consume it from foods such as cheese and sunflower seeds. Zinc compounds have a wide range of applications. For example, zinc oxide, ZnO is used in first aid tape and sunscreen. ZnO is also used to harden the rubber in boots and tires. ZnS is used to make some glow-in-the-dark paints. When pure zinc is exposed to air, the metal reacts with oxygen to form a protective oxide coating. This coating can prevent zinc-coated objects, such as bridges, from corroding easily.

Summary of properties (Zn)

Atomic weight65.38(2)
Discoverer (year)Andreas Marggraf (ancient times)
Natural formmetallic solid (hexagonal)
Electron configuration[Ar] 3d10 4s2
Melting point (ºC)420
Boiling point (ºC)907
Abundance in earth's crust (ppm)70
Isotope (abundance)64Zn (49.17), 66Zn (27.73), 67Zn (4.04), 68Zn (18.45), 70Zn (0.61)
Density g/cm37.13
Van der Waals radius (pm)201
Covalent radius (pm)120
Electronegativity (Pauling)1.81
Vaporization enthalpy (kJ/mol)115.50
Enthalpy of fusion (kJ/mol)7.32
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.39
Thermal conductivity (W/cm·K) at 25ºC and 1 atm1.160
Oxidation state+2
Electron affinity (eV)unstable ion
1st Ionization potential (eV)9.3942

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