Formula for iron oxide

Solution:

First examine the electron arrangement of the iron and oxygen atoms.

*Iron does not follow the rules in determining the Lewis diagram. This is a special case and unless you are an expert, you would not be expected to figure this out by yourself.

Write the Lewis symbols for each atom. See graphic on the left.

Determine the numbers of electrons which the atoms will lose and gain by applying the . Fe loses three electrons**. Oxygen gains two electrons to have an octet.
**Octet rule does not apply to iron.

The ionic bond between ions results from the electrostatic attraction of opposite charges.

The final formula of iron oxide is Fe2O3.