(ii) What are the ions present in these compounds?
The two sodium atoms lose 1 electron each to form 2 sodium ions (2Na + ).
The oxygen atom forms an oxide ion (O 2- ) by gaining 2 electrons, one from each sodium atom.
Na and O hence form an ionic compound Sodium Oxide (Na 2 O).
(ii) The ions present in sodium oxide compound (Na 2 O) are : Sodium ions ( Na + ) and oxide ions.( O 2- )
Magnesium oxide (MgO) is formed of Mg 2+ and O 2- ions.