an anion is any atom or group of atoms with a positive charge
In the physical sciences, an ion (/ˈaɪən, -ɒn/) is a particle that has a non-zero net electrical charge, such as an atom or molecule whose total number of electrons is not equal to its total number of protons. A cation is a positively-charged ion, while an anion is negatively charged. Because of their opposite electric charges, cations and anions attract each other and readily form ionic compounds, such as salts.
Ion