- An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons
- This loss or gain of electrons takes place to gain a full outer shell of electrons
- The electronic structure of an ion will be the same as that of a noble gas – such as helium, neon and argon
Ionisation of metals and non-metals
- Metals: all metals lose electrons to other atoms to become positively charged ions
- Non-metals: all non-metals gain electrons from other atoms to become negatively charged ions
- The positive and negative charges are held together by the strong electrostatic forces of attraction between opposite charges.
- This is what holds ionic compounds together
Example: Sodium Chloride, NaCl
- Sodium is a group 1 metal so will lose one outer electron to another atom to gain a full outer shell of electrons.
- A positive sodium ion with the charge +1 is formed.
- Chlorine is a group 7 non-metal so will need to gain an electron to have a full outer shell of electrons.
- One electron will be transferred from the outer shell of the sodium atom to the outer shell of the chlorine atom.
- A chlorine atom will gain an electron to form a negatively charged chloride ion with a charge of -1.
Formula of ionic compound: NaCl