 |  | | | Picture 3.1 A neutral atom that loses an electron becomes a positive ion. |
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| | Neutral atoms | | | | | | In ordinary matter, the number of electrons in an atom is the same as the number of protons. The positive and negative charges balance each other. Overall, the atom is uncharged (neutral). However, if something happens to make an atom lose or gain an electron then the atom will no longer be neutral. | | | |
| Atoms or ions | | | | | | An atom that gains or loses an electron becomes an ion. If it gains a negative electron, it becomes a negative ion. If it loses an electron it becomes a positive ion (see page 10 for more on ions). When a whole group of atoms (usually as part of an insulator) gain or lose electrons, this will cause static electricity (see page 11 for more on electrostatics). | | | |
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