Draw the Lewis structure for HCCN. Which answer below represents its VSEPR and molecular shape for the carbon in the structure that is underlined?
V trigonal planar
M: trigonal planar
V linear
Me trigonal planar
V: linear
M linear
V: tetrahedral
M: tetrahedral
V trigonal planar
M: bent
The Correct Answer and Explanation is :
The correct answer is:
V: linear
M: linear
Explanation:
The Lewis structure of HCCN consists of hydrogen (H), two carbon (C) atoms, and nitrogen (N). To determine its shape and molecular geometry using VSEPR (Valence Shell Electron Pair Repulsion) theory, we follow these steps:
1. Draw the Lewis Structure
- Hydrogen (H) has one valence electron.
- Carbon (C) has four valence electrons.
- Nitrogen (N) has five valence electrons.
- The total valence electrons available:
- H = 1
- C = 4 × 2 = 8
- N = 5
- Total = 14 electrons The most stable Lewis structure of HCCN follows the octet rule:
- Carbon forms a triple bond with nitrogen (C≡N).
- The other carbon forms a triple bond with the first carbon (C≡C).
- The hydrogen is attached to the first carbon. The structure is:
H–C≡C–N
2. Determine Molecular Shape Using VSEPR Theory
VSEPR theory predicts molecular shape by considering electron domains around the central atom. The two carbon atoms are important here.
- First carbon (C1) (connected to H and C):
- Electron domains: 2 (one single bond with H, one triple bond with C)
- VSEPR shape: Linear (AX2)
- Second carbon (C2) (connected to C and N):
- Electron domains: 2 (one triple bond with C, one single bond with N)
- VSEPR shape: Linear (AX2)
Thus, both carbons adopt a linear geometry. Since the question asks for the VSEPR and molecular geometry for one carbon, the answer is:
✔ VSEPR: Linear
✔ Molecular shape: Linear
This makes sense because both bonds around each carbon atom have 180° bond angles, making the molecule entirely linear.
Now, I will generate the Lewis structure image for HCCN.
Here is the Lewis structure diagram of the HCCN molecule. The diagram accurately represents the bonding structure, showing the single bond between H and C, the triple bond between C≡C, and the triple bond between C≡N, along with the lone pair on nitrogen.
Let me know if you need further clarifications!