Elemental Ions and Simple Salts

As discussed previously elemental ions can combine to form salts. These compounds are known as simple salts. These simple salts are a combination of metal cations and nonmetal anions. The common ions, their charges and names are listed below (the names of the cations are the same as the element, e.g., Ca2+ is the "calcium ion")

Naming simple ionic compounds:

The names of ionic compounds composed of the above ions are especially simple. The name of the compound is simply the name of the cation followed by the name of the anion, .e.g, K2S is potassium sulfide. Why is dipotassium sulfide incorrect? dipotassium sulfide is incorrect because potassium ion is always K+1 and sulfide is always S-2 and therefore the only way to combine them is K2S. Therefore there is a redundancy in the name dipotassium sulfide.

Naming simple ionic compounds with metals that have more than 1 charge:

Some metals have more than one charge. For example iron (Fe) has two possible ions, Fe+2 and Fe+3. When this happens the name of the ion is the element name and, in parenthesis next to it) a roman numeral denoting the charge. For iron this would be iron(II) and iron(III).

The names of ionic compounds with these ions must include these roman numerals. For example: FeCl2 has the name iron(II) chloride, Cr 2S3 has the name chromium(III) sulfide.

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C101 Class Notes
Prof. N. De Leon