How can I write the formula for aluminum oxide?
The formula for aluminum oxide is
The correct answer is
Let us see how we got the answer; Look at the electronic arrangement of Al and O atoms.
Al ( Z= 13) has 13 electrons with following electronic configuration. 1
It loses three electron in its 3s and 3p subshell to achieve stability and forms ion
O ( Z=8) on the other hand has eight electrons and wants to gain two electrons to achieve stable noble gas configuration.Oxygen atom on gaining two electrons forms negative oxide ion,
O ( Z=7) = 1
Three Oxygen atoms gains two electrons each ( total of six) from two Al atoms, each Al atom loses three electrons (total of six) to three oxygen atom , in this process each Al atom becomes
or the formula is