What is Salt

What Do Chemists Mean by 'Salt'?

We have all heard of salt, right? Those white crystals we put on our fries are the kind of salt we are most familiar with, but what do we really mean in chemistry when we refer to something as a salt?

In chemistry, a salt is an ionic compound which is made up of two groups of oppositely charged ions. The ion with a positive charge is called a cation, and the one with a negative charge is called an anion. How many of each type of ion the salt has is important because the compound must have an overall electrical charge of zero - that is, an equal balance between positive charge and negative charge.

Salts can be easily identified since they usually consist of positive ions from a metal with negative ions from a non metal.

What Are the Properties of a Salt?

The physical and chemical properties of materials are closely linked to how they are bonded together. We now know that ions in a salt are strongly attracted to each other, forming strong ionic bonds. It takes a lot of energy to break apart an ionic bond, and the stronger the attraction, the stronger the bond. This attraction between ions means that a compound with ionic bonds will have a strong, ordered structure.

Salts often form a crystal structure or crystal lattice, a highly ordered formation of molecules.

Finding a Salt's Chemical Formula

So far, we have only talked about sodium chloride, abbreviated NaCl, but all combinations of metals and nonmetals form salts. Examples include magnesium iodide, abbreviated MgI2, and aluminum oxide, Al2O3. Remember, we always write the cation first, followed by the anion. The number following the atom tells us how many of that atom type are contained in that compound; where there is no number, there is just one atom.

For aluminum oxide, there are two aluminum atoms and three oxygen atoms, but why that number? Why not just one of each, or one aluminum and two oxygens? Because the overall salt is always electrically neutral; in other words, the positive charge must equal the negative charge, so they cancel each other out. With different charges for each atom, some salts will demand different numbers of atoms for each element.