Positive Ions that Do Not Contain a Metal

Among inorganic compounds there are two common examples of positively charged ions that do not contain metals  

The NH4 ion also has the distinction of being our only example of a polyatomic positive ion besides Hg +. The NH4 ion is about the same size as the potassium ion (K ) and forms compounds very similar to potassium compounds. In fact, the ammonium ion is sometimes referred to as pseudoalkali metal ion. 

To say that an ion is a pseudoalkali metal ion is to say that it behaves like an alkali metal ion, but is not actually one. 

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