Question

Draw the Lewis structure for HCN. Indicate the hybrid orbitals, and draw a picture showing all the bonds between the atoms, labeling each bond as \(\sigma\) or \(\pi\).

Short answer

The Lewis structure for HCN is H-C≡N, with Carbon and Nitrogen having sp hybrid orbitals. There is one σ bond between Hydrogen and Carbon, and one σ bond and two π bonds between Carbon and Nitrogen.

Step-by-step solution

Determine the valence electrons

First, we need to find the total number of valence electrons for HCN. Hydrogen (H) has 1 valence electron, Carbon (C) has 4 valence electrons, and Nitrogen (N) has 5 valence electrons. Thus, the total number of valence electrons in HCN is: \(1 + 4 + 5 = 10\)

Arrange the atoms and form bonds

Now, arrange the atoms, placing the less electronegative atom (Carbon) in the center, and form a single bond between each pair of atoms: H-C-N

Complete the octets for the terminal atoms

After forming single bonds, we'll complete the octet for the terminal atoms - Hydrogen and Nitrogen. Since Hydrogen only needs 2 electrons to have a full shell, it's already satisfied. For Nitrogen, it currently has 2 electrons; we need to add 6 more electrons (3 lone pairs) to complete its octet: H-C≡N

Identify the hybrid orbitals for Carbon and Nitrogen atoms

Now, we need to identify the hybrid orbitals for Carbon and Nitrogen. Each of these atoms is connected to the other atoms through a triple bond, which means they are sp hybridized. In an sp hybridization, two orbitals mix to form two new hybrid orbitals, so both Carbon and Nitrogen will form two sp hybrid orbitals.

Draw the bonds and label them as σ or π

Finally, we need to draw the bonds between the atoms and label them as σ (sigma) or π (pi). There will be one σ bond and two π bonds between Carbon and Nitrogen, and one σ bond between Hydrogen and Carbon. The final structure is: H-C≡N (σ bond between H and C, one σ bond and two π bonds between C and N) So, the Lewis structure for HCN is H-C≡N, with each of Carbon and Nitrogen atom having sp hybrid orbitals, one σ bond between Hydrogen and Carbon, and one σ bond and two π bonds between Carbon and Nitrogen.