The molecular shape of Hydrogen Cyanide (HCN) is linear. This is because HCN consists of a hydrogen atom (H) bonded to a carbon atom (C), which is triple-bonded to a nitrogen atom (N). The carbon atom forms a single bond with hydrogen and a triple bond with nitrogen, resulting in a linear arrangement of atoms.
In HCN, the carbon atom has two regions of electron density: one from the single bond with hydrogen and one from the triple bond with nitrogen. These regions of electron density repel each other to maximize the distance between them, leading to a linear shape. The bond angle in HCN is 180 degrees, which is characteristic of a linear molecular geometry.
This linear shape is also influenced by the sp hybridization of the carbon atom. The sp hybridization results in two sp hybrid orbitals that are oriented in a straight line, further contributing to the linear molecular shape of HCN.