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Cations
- A cation forms when an atom loses one or more electrons from its outer (valence) shell (energy level).
- Cations are positively charged because the atom has more protons (+) than electrons (–).
- Mg atom has 12 protons and 12 electrons.
- Mg+2 ion has 12 protons and 10 electrons.
- Metal elements tend to form cations.
- Example
Anions
- An anion forms when an atom gains one or more electrons into its outer (valence) shell (energy level).
- Anions are negatively charged because the atom has less protons (+) than electrons (–).
- F atom has 9 protons and
9 electrons.
- F– ion has 9 protons and 10 electrons.
- Nonmetal elements tend to form anions.
- Example