Ions.If an atom or molecule has the same number of protons in its nucleus as it has electrons orbiting the nucleus, the atom or molecule is neutral and has no net charge. If there are more protons in the nucleus than orbiting electrons, the atom or molecule will have a net charge and is called an ion. As the charge is positive it will be a positive ion called a cation. If there are more orbiting electrons than protons in the nucleus, the atom or molecule will again and have a net charge and is called an ion, but as the charge is negative it will be a negative ion called an anion. There are a number of ways of producing ions but in electrochemistry salts in solution spontaneously disassociate into positively and negatively charged ions.

Further Information on this Topic can be found in the books of R.P.W. Scott by following the listed links