ionic compound: a compound made out of the ions of a metal and a nonmetal
cation: an ion with a positive charge, such as Na+ or Ca2+
anion: an ion with a negative charge, such as Cl− or S2−
stock system: a system of naming compounds by naming the ions that they’re made of. For example, a compound made of the ammonium ion and the chloride ion would be called “ammonium chloride”. All ionic compounds are named using the stock system.
· If the cation is a single element that has only one possible charge, the name of the cation is the name of the element. For example, the K+ ion is simply named “potassium”, and the Ca2+ ion is simply named “calcium”.
· If the element can have more than one possible charge, the name of the cation is the name of the element followed by a Roman numeral, indicating the charge, in paretheses. For example, chromium can make cations with three different charges:
|
Formula of Cation |
Name of Cation |
|
Cr2+ |
chromium (II) |
|
Cr3+ |
chromium (III) |
|
Cr6+ |
chromium (VI) |
· If the cation is a polyatomic ion, its name is the name of the polyatomic ion. For example, the NH4+ ion is named “ammonium”.
· If an anion is a single element, the name of the ion is the name of the element with the ending changed to “ide”. For example, the Cl− ion is made from chlorine, so it is called “chloride”. The O2− ion is made from oxygen, so it is called oxide.
· If the anion is a polyatomic ion, its name is just the name of the polyatomic ion. For example, the NO3− ion is named “nitrate”.