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
Arsenic Arsenic Arsen Arsenico Arsen

 
Atomic number: 33
Group numbers: 15
Period: 4
 
Discovery date: 1250
As

Arsenum
NEIGHBOURS
14
Si
 15
P
 16
S
32
Ge
 33
As
 34
Se
50
Sn
 51
Sb
 52
Te


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Arsenic was discovered by Albertus Magnus (Germany) in 1250. The origin of the name comes from the Greek word arsenikon meaning yellow orpiment. It is steel-grey, brittle semi-metal. Resists water, acids and alkalis. Tarnishes in air, burns in oxygen. Highly toxic by inhalation or ingestion.
Bottom NITROGEN GROUP Top

Relative atomic mass: 74.92160(2) Electronic configuration: [Ar] 3d10 4s2 4p3
Formal oxidation number: -3 +3 +5 Electronegativities: 2.18
Thermal conductivity: 50 W m-1 K-1 Electrical resistivity (20 °C): 33.3 μΩcm
Atomic radius: 124.5 pm Standard state (20 °C): solid
Density (g dm-3): 5780 (alpha, 293 K)
4700 (beta, 293 K)		 Molar volume (cm3 mol-1): 12.96 (alpha, 293 K)
15.94 (beta, 293 K)


Bottom THERMAL PROPERTIES Top

Melting point: 817 °C Heat of fusion: 27.7 kJ mol-1
Boiling point: 614 °C Heat of vaporization: 31.9 kJ mol-1
Critical temperature: 1827 °C Heat of atomization: 301.42 kJ mol-1


Bottom IONIZATION ENERGIES AND ABUNDANCE Top

1st ionization energy: 944.46 kJ mol-1 Abundance of element (air): - ppm
2nd ionization energy: 1797.82 kJ mol-1 Abundance of element (Earth's crust): 1 ppm
3rd ionization energy: 2735.48 kJ mol-1 Abundance of element (oceans): 0.003 ppm


Bottom ISOTOPES Top

Isotopes Relative atomic mass Abundance (%)
75As74.921596(2)100


Bottom MINERALS AND USES Top

Arsenic is found in mispickel (arsenopyrite). Many of its compounds are deadly poison and used as weed killer and rat poison. Used in semiconductors. Some compounds, called arsenides, are used in the manufacture of paints, wallpapers and ceramics. The price of 99.5 % pure arsenic sponge is 322.60 € for 100 g.

Bottom REDUCTION POTENTIALS Top

Balanced half-reaction   Eo / V      Annotation
H3AsO4 + 3H+ + 2e- = AsO+ + 3H2O +0.55  
H3AsO4 + 2H+ + 2e- = H3AsO3 + H2O +0.559  
H3AsO4 + 2H+ + 2e- = H3AsO3 + H2O +0.577  1 mol dm-3 HCl
H3AsO4 + 2H+ + 2e- = H3AsO3 + H2O +0.577  1 mol dm-3 HClO4
H2AsO4- + 3H+ + 2e- = H3AsO3 + H2O +0.666  
HAsO42- + 4H+ + 2e- = H3AsO3 + H2O +0.881  
HAsO42- + 3H+ + 2e- = H2AsO3- + H2O +0.609  
AsO43- + 3H2O + 2e- = H2AsO3- + 4OH- - 0.67  
2H3AsO4 + 4H+ + 4e- = As2O3(s) + 5H2O +0.58  
2H2AsO4- + 6H+ + 4e- = As2O3(s) + 5H2O +0.687  
2HAsO42- + 8H+ + 4e- = As2O3(s) + 5H2O +0.901  
2AsO43- + 10H+ + 4e- = As2O3(s) + 5H2O +1.27  
AsO43- + 8H+ + 5e- = As(s) + 4H2O +0.648  
As2O3(s) + 6H+ + 6e- = 2As(s) + 3H2O +0.234  
AsO+ + 2H+ + 3e- = As(s) + H2O +0.254  
H3AsO3 + 3H+ + 3e- = As(s) + 3H2O +0.248  
H2AsO3- + 4H+ + 3e- = As(s) + 3H2O +0.429  
H2AsO3- + H2O + 3e- = As(s) + 4OH- - 0.68  
As(s) + 3H+ + 3e- = AsH3(g) - 0.608  

 

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