Sodium chloride is a common salt that is produced from the evaporation of seawater or mineral-rich spring water in shallow pools. This process is used to produce table salt, which is used for flavouring food, in plastic production, and as a water conditioning agent and de-icing substance.
Despite its name, table salt has no odour but a distinct taste. It is soluble in water and is also hygroscopic, meaning it absorbs water from the atmosphere. It has a melting point of 801 degrees F and a boiling point of 1413 degrees C.
The physical properties of salt
Typical of ionic solids, NaCl is a good conductor of electricity when dissolved or in the molten state. Unlike magnesium oxide, which has the same ionic structure, it melts at a higher temperature.
When a crystal forms, the ions are organised into layers. You can see this in the diagrams below.
If you look at the first layer, you can see that it has eight chloride ions around the sodium. This is why it looks like they are touching each other – but they aren’t!
Now you can reverse that – put cesium ions in the center of the sodium, and the same arrangement. Now the ions in the sodium aren’t touching those in the cesium – and that introduces repulsion!
It’s because the cesium ions are bigger than the sodium ions – and so they aren’t in contact with each other. The attraction between the ions is still there, but there isn’t as much space for them to form repulsions with each other. And so they arrange themselves in a different way – which is why you get 6:6 coordination rather than 8:8!
