definition of ions
Atoms vs. Ions. Atoms are neutral; they contain the same number of protons as electrons. By definition, an ion is an electrically charged particle produced by either removing electrons from a neutral atom to give a positive ion or adding electrons to a neutral atom to give a negative ion. When an ion is formed, the number of protons does not change. Neutral atoms can be turned into positively charged ions by removing one or more electrons. A neutral sodium atom, for example, contains 11 protons and 11 electrons. By removing an electron from this atom we get a positively charged Na + ion that has a net charge of +1. Atoms that gain extra electrons become negatively charged.