Question

What is the chemical formula for ionic compounds formed when elements of $Ca$ and $N$ react?

Answer 1

The formation of ionic bonds takes place by transference of electrons in between atoms. The electronegativity difference between them is greater than $1.5$ . To write the chemical formula cation which is electropositive should be written first and then anion that is electronegative with respect to their valency.

Complete step by step answer:
Calcium nitride is found to be a reddish brown and crystalline solid in nature that is made up of calcium and nitrogen. The chemical formula for calcium nitride is $Ca{}_3N{}_2$. We can determine the ratio by the charges present on the ions.
$(3C \times Ca{}^{2 + }) = + 6$
$(2 \times N{}^{3 - }) = - 6$
Therefore the net charge of the compound is zero.
This calcium nitride is formed along with the oxides like calcium oxide, when calcium is burned in air. It can possibly be formed by direct reaction of the elements.
The reaction can be written as followed.
$3{\text{ }}Ca{\text{ }} + {\text{ }}N{}_2{\text{ }} \to {\text{ }}Ca{}_3N{}_2$

Note:
When it comes to the calcium nitrogen compounds, there are many possibilities of the formation of products that could be calcium nitride, calcium nitrate, or calcium nitrite, etc. Calcium belong to group two metal so it can lose two electrons and formation of calcium ion with a $+ 2$ valency where as nitrogen which belongs to group $15$ that requires three extra electrons to form nitride with a $- 3$ valency due to electrostatic force of attraction the formation of calcium nitride takes place. For calcium nitrate it is $Ca\left( {NO{}_3} \right){}_2$ and calcium nitrite it is $Ca\left( {NO{}_2} \right)$ . Nitrate and nitride is known to be polyatomic anions.