How can I write the formula for aluminum oxide?

1 Answer
Manish Bhardwaj · Meave60 · Dwayne M. · dwayne
Jul 3, 2014

The formula for aluminum oxide is #Al_2O_3#.

Explanation:

The correct answer is #Al_2O_3#.

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#s^2#2#s^2#2#p^6#3#s^2#3#p^1#

It loses three electron in its 3s and 3p subshell to achieve stability and forms ion #Al^(3+)#.

#Al^(3+)# = 1#s^2#2#s^2#2#p^6#

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^(2-)# ion.

O ( Z=7) = 1#s^2#2#s^2#2#p^4#

#O^(2-)# = 1#s^2#2#s^2#2#p^6#

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 #Al^(3+)# ion and Oxygen atom after gaining two electrons becomes #O^(2-)# ion.

http://gallery4share.com/a/aluminum-ion-lewis-dot-structure.html

2#Al^(3+)# and 3 #O^(2-)#

or the formula is #Al_2O_3#.

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