Ions and ionic bonds
Ions
- An ion is an atom (or group) that has lost or gained electrons, so it has a charge.
- A metal atom loses electrons → a positive ion (cation).
- A non-metal atom gains electrons → a negative ion (anion).
- Atoms do this to reach a full outer shell, like a noble gas.
Practice
A metal atom forms an ion by:
Metals lose their outer electrons to form positive ions (cations); non-metals gain electrons (anions).
Practice
Atoms form ions to reach a full outer electron shell, like a noble gas.
Gaining or losing electrons gives the ion a stable full outer shell.
The ionic bond
- An ionic bond is the strong electrostatic attraction between oppositely charged ions.
- It forms between a metal and a non-metal.
- Example — NaCl: sodium (2,8,1) gives its outer electron to chlorine (2,8,7). Now $\text{Na}^{+}$ (2,8) and $\text{Cl}^{-}$ (2,8,8) — both full, and the opposite charges attract.
Practice
An ionic bond is:
Ionic bonding is the strong attraction between positive and negative ions, formed between a metal and a non-metal.
You've got it
Key idea
- ion = atom that lost/gained electrons; metals lose (cation +), non-metals gain (anion −)
- atoms do this to reach a full outer shell
- an ionic bond = electrostatic attraction between + and − ions (metal + non-metal)