Periodic Table of the Elements
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Bottom FACULTY OF CHEMICAL TECHNOLOGY o PERIODIC TABLE OF THE ELEMENTS Bottom
  A B C D E F G H I J K L M N O P R S T U V X Z  
Periodic Table of the Elements Tableau périodique des éléments Periodni sustav elemenata Tavola periodica degli elementi Das Periodensystem der Elemente
Manganese Manganèse Mangan Manganese Mangan

 
Atomic number: 25
Group numbers: 7
Period: 4
 
Discovery date: 1774
Mn

Manganum
NEIGHBOURS

 
 
 
24
Cr
 25
Mn
 26
Fe
42
Mo
 43
Tc
 44
Ru


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Manganese was discovered by Johann Gahn (Sweden) in 1774. The origin of the name comes from the Latin word magnes meaning magnet, or magnesia nigri meaning black magnesia (MnO2). It is hard, brittle, grey-white metal with a pinkish tinge. Impure forms are reactive. Rusts like iron in moist air.
Bottom TRANSITION ELEMENT: MANGANESE GROUP Top

Relative atomic mass: 54.938049(9) Electronic configuration: [Ar] 3d5 4s2
Formal oxidation number: +2 +3 +4 +7 Electronegativities: 1.55
Thermal conductivity: 7.82 W m-1 K-1 Electrical resistivity (20 °C): 144 μΩcm
Atomic radius: 136.7 pm Standard state (20 °C): solid
Density (g dm-3): 7440 (alpha, 293 K)
6430 (m.p.)		 Molar volume (cm3 mol-1): 7.38 (alpha, 293 K)
8.54 (m.p.)


Bottom THERMAL PROPERTIES Top

Melting point: 1246 °C Heat of fusion: 14.4 kJ mol-1
Boiling point: 2061 °C Heat of vaporization: 220.5 kJ mol-1
Critical temperature: 4054 °C Heat of atomization: 279.37 kJ mol-1


Bottom IONIZATION ENERGIES AND ABUNDANCE Top

1st ionization energy: 717.28 kJ mol-1 Abundance of element (air): - ppm
2nd ionization energy: 1509.04 kJ mol-1 Abundance of element (Earth's crust): 1400 ppm
3rd ionization energy: 3248.49 kJ mol-1 Abundance of element (oceans): 0.002 ppm


Bottom ISOTOPES Top

Isotopes Relative atomic mass Abundance (%)
55Mn54.938050(1)100


Bottom MINERALS AND USES Top

Manganese is most abundant ores are pyrolusite (MnO2), psilomelane [(Ba,H2O)2Mn5O10] and rhodochrosite (MnCO3). Pure metal produced by mixing MnO2 with powered Al and ignited in a furnace. Used in steel, batteries and ceramics. The steel in railroad tracks can contain as much as 1.2% manganese. It is crucial to the effectiveness of vitamin B1. The price of 99.9 % pure manganese pieces is 87.80 € for 1000 g.

Bottom REDUCTION POTENTIALS Top

Balanced half-reaction   Eo / V      Annotation
MnIV + e- = MnIII +1.65  14 mol dm-3 H2SO4
MnIII + e- = MnII +1.59  14 mol dm-3 H2SO4
Mn3+ + e- = Mn2+ +1.51  7.5 mol dm-3 H2SO4
Mn2+ + 2e- = Mn(s) - 1.180  
MnO4- + e- = MnO42- +0.564  
MnO4- + 2H2O + 3e- = MnO2(s) + 4OH- +0.588  
MnO4- + 4H+ + 3e- = MnO2(s) (alfa) + 2H2O +1.695  
MnO4- + 4H+ + 3e- = MnO2(s) (beta) + 2H2O +1.679  
MnO4- + 8H+ + 4e- = Mn3+ + 4H2O +1.506  
MnO4- + 8H+ + 5e- = Mn2+ + 4H2O +1.51  
MnO42- + 4H+ + 2e- = MnO2(s) + 2H2O +2.257  
MnO42- + 5H+ + 2e- = HMnO2- + 2H2O +1.234  
MnO42- + 2H2O + 2e- = MnO2(s) + 4OH- +0.51  18 °C
MnO2(s) + 4H+ + e- = Mn3+ + 2H2O +0.948  
MnO2(s) (alfa) + 4H+ + 2e- = Mn2+ + 2H2O +1.23  
MnO2(s) (beta) + 4H+ + 2e- = Mn2+ + 2H2O +1.22  
MnO2(s) (gama) + 4H+ + 2e- = Mn2+ + 2H2O +0.21  
Mn(OH)3(s) + e- = Mn(OH)2(s) + 2OH- +0.1  
Mn(CN)63- + e- = Mn(CN)64- - 0.244  
Mn(OH)2(s) + 2e- = Mn(s) + 2OH- - 1.55  
HMnO2- + 3H+ + 2e- = Mn(s) + 2H2O - 0.163  

 

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