How many sigma and pi bonds does ##"Ca"("CN")_2## contain?

You get 2 sigma and 4 per formula unit of calcium cyanide.

First, it must be noted that calcium cyanide, ##"Ca"("CN")_2##, is an made up of one calcium cation, ##"Ca"^(2+)##, and two cyanide anions, ##"CN"^(-)##.

This means that you must look for and in the structure of the cyanide ion, since the between the calcium atom and the two cyanide ions is mostly in nature.

Before taking a look at the of the cyanide ion, remember that you have

• single bond ##->## one sigma bond and no pi bonds;
• double bond ##->## one sigma bond and one pi bond;
• triple bond ##->## one sigma bond and two pi bonds.

So, the Lewis structure of the cyanide ion looks like this

Notice that you have a triple bond between the carbon atom and the nitrogen atom. This means that you get one sigma bond and two pi bonds per cyanide ion.

Since the formula unit of calcium cyanide contains 2 cyanide ions, you will end up with a total of

• two ;
• four pi bonds.