Question

What is the ionic compound formed when oxygen reacts with aluminium $?$

Answer 1

Hint : Oxygen $({O_2})$ is a divalent diatomic gas and is present in abundance in the earth atmosphere $.$ Aluminium $(Al)$ is trivalent metal which is the third most abundant metal present in the earth $'$s crust $.$ An ionic bond is formed by the gaining or losing of electrons $.$

Complete Step By Step Answer:
An ionic bond is formed between two atoms when one loses its electrons and the other accepts the electrons $.$ This is the most common bond formed metal and non-metal elements $.$ Here $,$ the metal donates electron whereas the non-metal accepts it $.$ There should be electronegativity difference between both $.$ Electron gaining and losing depends on the outer electron configuration of the atoms $.$ At last $,$ the ultimate aim of every atom is to attain stability by having an octet electron configuration $.$
Aluminium is a group 3 element $.$ Its electronic configuration is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}$ or $\left[ {Ne} \right]3{s^2}3{p^1}$
It has three valence electrons in its outer orbital $\left[ {3{s^2}3{p^1}} \right]$ $.$ It is ready to donate its $3$electrons in order to gain octet configuration and become stable$.$
Oxygen is a group 16 element $.$ Its electronic configuration is $1{s^2}2{s^2}2{p^4}$ or $\left[ {He} \right]2{s^2}2{p^4}$.
In this case, oxygen has to gain two more electrons in order to attain a stable octet configuration. Oxygen being a highly electronegative element gains these electrons from the electropositive aluminium metal atom.
From this we can understand that $Al$ donates its $3$ electrons to ${O_2}$ $,$ and each $O$ atom has to gain $1$ pair of electrons from $Al$ to complete its octet configuration $.$
Therefore $,$ the balanced chemical equation for the above reaction is:
$4Al + 3{O_2} \to 2A{l_2}{O_3}$
$($Check the number of atoms and charge balance on both sides of the equation $)$
The product is Aluminium oxide $,$ $A{l_2}{O_3}$, commonly called as alumina $.$

Note :
$(i)$ In the given product $,$ $Al$is present in $+ 3$ oxidation state and ${O_2}$is in $- 2$ oxidation state $.$
$(ii)$ Aluminium oxide is amphoteric in nature $,$i$.$e $,$ it reacts with both acids and bases $.$
$(iii)$ Though metals are excellent conductors of electricity $,$ $A{l_2}{O_3}$is an electrical insulator $.$