Forming Ions (DP IB Chemistry): Revision Note

Forming ions

How are ions formed?

• As a general rule, metals are on the left of the Periodic Table and non-metals are on the right-hand side

• Ionic bonds involve the transfer of electrons from a metallic element to a non-metallic element

• Transferring electrons usually leaves the metal and the non-metal with a full outer shell

• Metals lose electrons from their valence shell forming positively charged cations

How a sodium atom forms a sodium ion 

• Non-metal atoms gain electrons forming negatively charged anions

How a chlorine atom forms a chloride ion  

• Once the atoms become ions, their electronic configurations are the same as a noble gas.

  • A sodium ion (Na⁺) has the same electronic configuration as a neon atom (Ne): [2,8]

  • A chloride ion (Cl^-) also has the same electronic configuration as an argon atom (Ar): [2,8,8]