ABSTRACT
Iodine is sparingly soluble in water, but it is readily dissolved in nonpolar solvents. The presence of iodine always reduces the surface tension of a solvent. An interesting property of iodine solutions is their color that can be violet, red, or brown. A comprehensive survey of these would be impossible; instead, discussion will be centered primarily on those which are relevant to protein labeling reactions. Halides are compounds of two elements, one of which is a halogen. Iodine form salts with many metals to yield iodides. Isotopes are atoms with the same atomic number but different mass numbers. Mass number is the sum of protons and neutrons in a nucleus expressed as the nearest integer of the nuclide’s atomic mass. There are natural and artificial isotopes and, in both cases, an isotope is either stable or unstable.
