Sodium chloride which is commonly referred to as table salt, has many interesting properties. There is a one to one ratio of sodium to chlorine atoms. The bonding that occurs between atoms is an ionic bond due to the difference in charge between the sodium and the chlorine atoms. The crystalline structure that forms is a cubic structure. The crystals are called face centered cubic symmetry with each ion surrounded by six ions of the opposite type. Rock salt or halite also contains cubic crystals. Salt causes water to be drawn out of materials by osmosis. Therefore, it has been used historically as a preservative, or as a way of drying out foods to preserve shelf life. It can draw water out of bacteria in foods, killing bacteria and preserving the length of time the food remains unspoiled.
Sodium chloride is a substance and it's properties are it's characteristic qualities.
Sodium chloride could have different forms:
- fine grains of salt (this is the table salt);
- salt crystals whose diameters have up to 3 mm;
- crystals of rock salt, whose diameters have 5cm or more.
No matter the differences between these samples of salt, they have the same fundamental properties.
The crystals from each sample are bounded by square or rectangular faces. Each face is always at right angle to each adjacent face.
The crystals of salt break along planes parallel to the original faces.
The taste of all samples, no matter the size, is salty.
Also, the density of the salt, no matter the size, doesn't change:2.163 cm^-3.
Also, there are many other physical properties that can be measured exactly: hardness, malleability, electric and thermal conductivity, ductility and melting point.