The bond angle of Hydrogen Cyanide (HCN) is 180 degrees. This is because HCN is a linear molecule. In a linear molecule, the atoms are arranged in a straight line, and the bond angle between the atoms is 180 degrees.
In HCN, the carbon atom is triple-bonded to the nitrogen atom and single-bonded to the hydrogen atom. The triple bond between carbon and nitrogen consists of one sigma bond and two pi bonds, which results in a linear arrangement of the atoms. This linear arrangement ensures that the bond angle is 180 degrees.
Understanding the bond angle is crucial in predicting the molecular geometry and the physical and chemical properties of the molecule. In the case of HCN, the linear geometry and the 180-degree bond angle contribute to its polarity and reactivity.