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Iodine, including Technical Data, Safety Data and its high purity propertiesresearch, applications and other useful facts are discussed below. Scientific facts such as the atomic structure,ionization energyabundance on Earthconductivity and thermal properties are included.

Iodine compounds with many elements, but is less active than the other halogens, which displace it from iodides. Iodine exhibits some metallic-like properties. It dissolves readily in chloroform, carbon tetrachloride, or carbon disulfide to form purple solutions. It is only slightly soluble in water. Iodine compounds are important in organic chemistry and very useful in medicine. Iodides, and thyroxine which contains iodine, are used internally in medicine. Potassium iodide finds use in photography. Iodine is found mainly as the highly water-soluble iodide I-.The deep blue colorwith starch solution is characteristic of the free element. Iodine is available in compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity).

Iodine is a Block P, Group 17, Period 5 element. The number of electrons in each of Iodine‘s shells is 2, 8, 18, 18, 7 and itselectronic configuration is [Kr] 4d10 5s2 5p5. In its elemental form iodine‘s CAS number is 7553-56-2. The iodine atom has a radius of and it‘s Van der Waals radius is Iodine in large amounts is poisonous but in small doses is only slightly toxic. 

Abundance. The following table shows the abundance of iodine and each of its naturally occurringisotopes on Earth along with the atomic mass for each isotope.

Isotope Atomic Mass % Abundance on Earth
I-120 119.91005 -
I-121 120.90737 -
I-122 121.90760 -
I-123 122.905605 -

The following table shows the abundance of Iodine present in the human body and in the universe scaled to parts per billion (ppb) by weight and by atom:
  Typical Human Body Universe
by Weight 200 ppb 1 ppb
by Atom 10 atoms relative to C = 1000000 0.01 ppb

Safety Data and Biological Role. The safety data for Iodine metalnanoparticles and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the left margin. Iodinecompounds have no biological role. 

Ionization Energy. The ionization energy for iodine(the least required energy to release a single electron from the atom in it‘s ground state in the gas phase) is stated in the following table:
1st Ionization Energy 1008.4 kJ mol-1
2nd Ionization Energy 1845.8 kJ mol-1
3rd Ionization Energy 3184 kJ mol-1

Conductivity. As to iodine‘s electrical and thermal conductivity, the electrical conductivity measured in terms of electrical resistivity @ 20 ?C is1.3×107Ω·m and its electronegativities (or its ability to draw electrons relative to other elements) is 2.66. The thermal conductivity of radium is 0.45W m-1 K-1. 

Thermal Properties. The melting point and boiling point for iodine are stated below. The following chart sets forth the heat of fusion, heat of vaporization and heat of atomization.

Heat of Fusion 15.52 kJ mol-1 of I2
Heat of Vaporization 41.57 kJ mol-1 of I2
Heat of Atomization 107 kJ mol-1

Formula Atomic Number Molecular Weight Electronegativity (Pauling) Density Melting Point Boiling Point Vanderwaals radius Ionic radius Energy of first ionization
I 53 53 2.66 4.933 g·cm-3 113.7 °C 184.3 °C 198 pm 206pm 1008.4 kJ mol-1