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Iodine is a toxic purple-black solid with a slight metallic lustre. At room temperature it sublimes slowly to give a violet vapour with an irritating odour. A member of the halogen family of elements, it is not found free in nature, but seawater contains small amounts of dissolved iodide ions. ‘Tincture of iodine’, used to disinfect wounds, contains iodine dissolved in a mixture of water and ethanol.
The atoms in the molecule are connected by a single covalent bond. A covalent bond is formed when atoms share electrons and a single covalent bond has two shared electrons, one contributed by each atom. Because the electrons in the bond are shared equally by the two iodine atoms, the molecule does not have an electric dipole.
The type of model shown here, called a ball-and-stick model, is one of several ways of modelling molecules. This type is useful because it clearly shows the geometry of the molecule and the order (single, double or triple) of the bonds. However, because 'sticks' are used to represent bonds, this type of model does not represent the actual shape of the molecule as well as 'space-filling' models do.