When an atom or molecule loses or gains electron, ion is formed. When an atom or molecule loses electron it becomes positively charged because the number of protons in this atom are greater than electrons. It is a positive ion and also known as cation. When an atom gains an electron it becomes negative ion because the number of electrons in the atom is greater than number of protons. It is also known as anion. Moreover, the flow of these charges produces electric current.
A positive ion share with the electrons and it didn't change when you compared with it so and the negative ion is something share with the protons so it say together