The Structure Of Sodium Hydroxide
Sodium Hydroxide is a vital industrial chemical that has also recently found an increasingly important role in the production of biodiesel from used and new vegetable oils. It is an ionically bonded compound that is white in solid form colourless as a liquid. It also goes by the names lye and caustic soda. It is an highly toxic chemical and must be handled with extreme caution. What Is It Composed Of? This compound has the chemical formula NaOH. It is an ionically bonded compound, which means it is the combination of a metal and a non metal. The metal part carries a positive charge and the non metal carries a negative charge. In this case the metal is Sodium, with the symbol Na. Sodium is most stable when it has a full outer shell of eight electrons, and it does this by discarding its outermost electron. This leaves Sodium with a charge of +1. 
The non metal part is called a hydroxide ion which is effectively a water molecule with one of its Hydrogen atoms removed. The Hydroxide ion carries an overall charge of -1. This ion is an extremely reactive ion that will readily bond with any spare Hydrogen ion (also known as a proton) and thus turn back into water. Hydroxide does not occur naturally most of the time because of its reactivity. It requires energy to split water into a hydrogen ion and hydroxide. The images below show the formation of water from its constituent atoms, then the splitting of water into hydroxide and a hydrogen ion.
Structure of the Solid The ratio of Sodium ions and Hydroxide ions required to make a neutral compound is 1:1 as they both have the same degree of charge. We can see a simplified view of the packing of the ions in solid NaOH shown to the right. Note that the hydroxide ions are shown as simple balls for clarity's sake.
While the actual structure of solid NaOH is not as uniform as shown due to the larger size of the Hydroxide ions, the structure shown gives us a good idea of how the different ions pack together to form the solid salt.
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