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
Iodine Iode Jod Iodio Iod

 
Atomic number: 53
Group numbers: 17
Period: 5
 
Discovery date: 1811
I

Iodum
NEIGHBOURS
34
Se
 35
Br
 36
Kr
52
Te
 53
I
 54
Xe
84
Po
 85
At
 86
Rn


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Iodine was discovered by Bernard Courtois (France) in 1811. The origin of the name comes from the Greek word iodes meaning violet. It is shiny, black, non-metallic solid with characteristic odour. Sublimes easily and as a gas it is violet and intensely irritating to the eyes, nose and throat.
Bottom HALOGENS ELEMENT Top

Relative atomic mass: 126.90447(3) Electronic configuration: [Kr] 4d10 5s2 5p5
Formal oxidation number: -1 +1 +5 +7 Electronegativities: 2.66
Thermal conductivity: 0.449 W m-1 K-1 Electrical resistivity (20 °C): 1.3E+15 μΩcm
Atomic radius: 133.1 pm Standard state (20 °C): solid
Density (g dm-3): 4930 (293 K) Molar volume (cm3 mol-1): 25.74 (293 K)


Bottom THERMAL PROPERTIES Top

Melting point: 113.7 °C Heat of fusion: 15.27 kJ mol-1
Boiling point: 184.4 °C Heat of vaporization: 41.67 kJ mol-1
Critical temperature: 546 °C Heat of atomization: 107.24 kJ mol-1


Bottom IONIZATION ENERGIES AND ABUNDANCE Top

1st ionization energy: 1008.40 kJ mol-1 Abundance of element (air): - ppm
2nd ionization energy: 1845.90 kJ mol-1 Abundance of element (Earth's crust): 0.5 ppm
3rd ionization energy: 3184.04 kJ mol-1 Abundance of element (oceans): 0.05 ppm


Bottom ISOTOPES Top

Isotopes Relative atomic mass Abundance (%)
127I126.904468(4)100


Bottom MINERALS AND USES Top

Iodine occurs on land and in the sea in sodium and potassium compounds. Required in small amounts by humans. Once used as an antiseptic, but no longer due to its poisonous nature. The price of 99.5 % pure crystalline iodine is 140.50 € for 1000 g.

Bottom REDUCTION POTENTIALS Top

Balanced half-reaction   Eo / V      Annotation
I2(s) + 2e- = 2I- +0.535  
I2(aq) + 2e- = 2I- +0.615  
3I2 + 2e- = 2I3- +0.789  
I3- + 2e- = 3I- +0.536  
H5IO6 + H+ + 2e- = IO3- + 3H2O +1.601  
HIO52- + 3H+ + 2e- = IO3- + 2H2O +1.898  
HIO52- + 8H+ + 6e- = HIO + 4H2O +1.389  
2HIO52- + 18H+ + 14e- = I2(s) + 10H2O +1.384  
3HIO52- + 27H+ + 22e- = I3- + 15H2O +1.357  
HIO52- + 9H+ + 8e- = I- + 5H2O +1.288  
HIO4 + 2H+ + 2e- = HIO3 + H2O +1.626  
IO4- + 2H+ + 2e- = IO3- + H2O +1.653  
HIO4 + 6H+ + 6e- = HIO + 3H2O +1.290  
IO4- + 7H+ + 6e- = HIO + 3H2O +1.235  
2HIO4 + 14H+ + 14e- = I2(s) + 8H2O +1.300  
3HIO4 + 21H+ + 22e- = I3- + 12H2O +1.276  
HIO4 + 7H+ + 8e- = I- + 4H2O +1.215  
IO3- + 6H+ + 4e- = I+ + 3H2O +1.155  
IO3- + 4H+ + 4e- = IO- + 2H2O +0.972  
2IO3- + 12H+ + 10e- = I2(s) + 6H2O +1.196  
2IO3- + 12H+ + 10e- = I2(aq) + 6H2O +1.178  
IO3- + 2Cl- + 6H+ + 4e- = ICl2- + 3H2O +1.24  
2HIO3 + 10H+ + 10e- = I2(s) + 6H2O +1.169  
3HIO3 + 15H+ + 16e- = I3- + 9H2O +1.145  
HIO3 + 5H+ + 6e- = I- + 3H2O +1.078  
2HIO + 2H+ + 2e- = I2(s) + 2H2O +1.354  
2IO- + 4H+ + 2e- = I2(s) + 2H2O +2.005  
3HIO + 3H+ + 4e- = I3- + 3H2O +1.213  
3IO- + 6H+ + 4e- = I3- + 3H2O +1.701  
IO- + 2H+ + 2e- = I- + H2O +1.313  
HIO + H+ + 2e- = I- + H2O +0.987  
2ICl3(s) + 6e- = I2(s) + 6Cl- +1.28  
2ICl(s) + 2e- = I2(s) + 2Cl- +1.22  
2ICl + 2e- = I2(s) + 2Cl- +1.19  
2ICl2- + 2e- = I2(s) + 4Cl- +1.056  
2IBr(aq) + 2e- = I2(s) + 2Br- +1.02  

 

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