Different types of bases

1. Organic molecules
   You can think of amines, and of amino acids (see module 11)
   
   
2. Negative ions
   In principle, all negative ions can receive, capture H⁺ ions. So they are always bases, strong or weak.
   
   
3. some positive ions
   Those cations, after having donated H⁺, can take back that H⁺ ion and thus act as a base.
   
   
4. Some neutral molecules; more hereover later.