Sodium azide is a white crystalline powder consisting of positive sodium ion and negative azide ions. The azide ion is the 'interesting' part of the molecule and is the part which is responsible for much of the molecules' reactivity.
The azide group is made up three nitrogen atoms joined together. This is a very unstable arrangement and consequently the azide will readily react to gain the more stable configuration of nitrogen gas which only has two atoms of nitrogen bonded together. This is the driving force of the explosive reactions of sodium azide.
Sodium azide is not only explosively reactive, it is also extremely toxic and is, in fact, as powerful as a poison as sodium cyanide and ingesting very small amounts can cause death in less than half an hour. It is a metabolic poison which inhibits certain key enzymes and has a serious effect on the cardiovascular system.
It has many uses in today's society: