ZINC

TRANSITION ELEMENT: ZINC GROUP

Atomic number:	30
Group numbers:	12
Period:	4
Electronic configuration:	[Ar] 3d¹⁰ 4s²
Formal oxidation number:	+2
Electronegativities:	1.65
Atomic radius / pm:	133.5
Relative atomic mass:	65.38(2)

Zinc has been known since ancient times. The origin of the name comes from the German word zink. It is a bluish-silver, ductile metal that reacts with alkalis and acids. Zinc tarnishes in air. Zinc is found in the minerals zinc blende (sphalerite) (ZnS), calamine, franklinite, smithsonite (ZnCO3), willemite and zincite (ZnO). It is used to coat other metal (galvanizing) to protect them from rusting, 90% of the zinc is used for galvanizing steel. Zinc metal is used in the common dry-cell batteries and to make alloys such as brass, bronze. Zinc compounds are used in the manufacture of paints, cosmetics, plastics, electronic devices, and many other products. The price of 99.99 % pure zinc granules is 39.60 € for 500 g.

PHYSICAL PROPERTIES
Density / g dm^-3:	7133	(293 K)
	6577	(m.p.)
Molar volume / cm³mol^-1:	9.17	(293 K)
	9.94	(m.p.)
Electrical resistivity / µΩcm:	5.964	(20 °C)

THERMAL PROPERTIES
Thermal conductivity / W m^-1K^-1:	116
Melting point / °C:	419.53
Boiling point / °C:	907
Heat of fusion / kJ mol^-1:	6.67
Heat of vaporization / kJ mol^-1:	114.2
Heat of atomization / kJ mol^-1:	130.181

IONIZATION ENERGIES
First ionization energy / kJ mol^-1:	906.41
Second ionization energy / kJ mol^-1:	1733.31
Third ionization energy / kJ mol^-1:	3832.71

ABUNDANCE OF ELEMENT
in the atmosphere / ppm:	-
in the Earth's crust / ppm:	80
in the oceans / ppm:	0.01

CRYSTALLOGRAPHIC DATA
Crystal structure:	hexagonal
Unit-cell dimensions / pm:	a=266.47, c=494.69
Space group:	P6₃/mmc

ISOTOPES
Isotope	Relative atomic mass	Mass percent (%)
⁶⁴Zn	63.929147(2)	48.6(3)
⁶⁶Zn	65.926037(2)	27.9(2)
⁶⁷Zn	66.927131(2)	4.1(1)
⁶⁸Zn	67.924848(2)	18.8(4)
⁷⁰Zn	69.925325(4)	0.6(1)

REDUCTION POTENTIALS
Balanced half-reaction	E^o / V
Zn²⁺ + 2e^- → Zn(s)	- 0.763
ZnO₂^2- + 4H⁺ + 2e^- → Zn(s) + 2H₂O	+0.441
HZnO₂^- + 3H⁺ + 2e^- → Zn(s) + 2H₂O	- 0.054
ZnO₂^2- + 2H₂O + 2e^- → Zn(s) + 4OH^-	- 1.216
Zn(OH)₂(s) + 2e^- → Zn(s) + 2OH^-	- 1.245
ZnS(s) + 2e^- → Zn(s) + S^2-	- 1.40
Zn(NH₃)₄²⁺ + 2e^- → Zn(s) + 4NH₃	- 1.04
Zn(CN)₄²⁺ + 2e^- → Zn(s) + 4CN^-	- 1.26