What is the ratio of potassium atoms to oxygen atoms in a binary compound made from these two elements?
When combined with other elements, potassium (K) always forms a
+1 ion. Oxygen (O), when combined with other elements almost always
(with a few rare exceptions) forms a -2 ion. Therefore, when these
combine to form a binary compound, the charges must balance out.
Therefore there must be 2 K+ ions for each O2- ion because 2*1 =
So the ratio must be 2 potassiums for each oxygen.
Three potassium oxides are known:
- K2O: 2 potassium atoms and 1 oxygen atom
- KO2: 1 potassium atoms and 2 oxygen atoms
- K2O2: 2 potassium atoms and 2 oxygen atoms