What is the molecular geometry n the electron domain for HCN
To determine the molecular geometry and electron domain of HCN (hydrogen cyanide), we need to follow these steps:
Step 1: Draw the Lewis structure of HCN:
- Hydrogen (H) has 1 valence electron.
- Carbon (C) has 4 valence electrons.
- Nitrogen (N) has 5 valence electrons.
H: C N
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H - C ≡ N
Step 2: Determine the total number of valence electrons.
The number of valence electrons in HCN is the sum of valence electrons of all the atoms. In this case, we have:
1 Hydrogen (H) atom x 1 valence electron = 1 valence electron
1 Carbon (C) atom x 4 valence electrons = 4 valence electrons
1 Nitrogen (N) atom x 5 valence electrons = 5 valence electrons
Total = 1 + 4 + 5 = 10 valence electrons
Step 3: Determine the central atom.
The least electronegative atom (C in this case) is usually the central atom.
Step 4: Place the remaining electrons around the central atom.
Using single bonds, connect the outer atoms to the central atom. In this case, connect C and N with a triple bond (≡).
⇒ H - C ≡ N
Now, distribute the remaining electrons around the atoms to fulfill the octet rule.
Since C and N already have 8 electrons, only Hydrogen (H) needs to fulfill its octet rule.
⇒ H: C N
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H - C ≡ N
Step 5: Determine the electron domain.
Count the total number of bond pairs and lone pairs around the central atom. In this case, the C atom has a triple bond (3 bond pairs). There are no lone pairs on C.
Therefore, the electron domain for C is 3.
Step 6: Determine the molecular geometry.
Based on the number of electron domains, we can determine the molecular geometry using the following guidelines:
- 3 electron domains → Trigonal planar geometry.
So, the molecular geometry of HCN is trigonal planar.
I hope this helps! Let me know if you have any further questions.
To determine the molecular geometry and electron domain geometry of a molecule like HCN (hydrogen cyanide), we can use the Valence Shell Electron Pair Repulsion (VSEPR) theory. This theory states that electron pairs around a central atom repel each other, so they arrange themselves in a way to minimize this repulsion.
1. Start by determining the Lewis structure of HCN:
- Hydrogen (H) has one valence electron.
- Carbon (C) has four valence electrons.
- Nitrogen (N) has five valence electrons.
In the Lewis structure, the hydrogen atom will form a single bond with the carbon atom, and the carbon atom will form a triple bond with the nitrogen atom. This gives us:
H:C::N:
2. Determine the total number of electron domains (regions of electron density) around the central atom (carbon, C). In this case, there are three electron domains: one single bond, one triple bond, and one lone pair on the nitrogen atom.
3. Use the electron domain arrangement to determine the molecular geometry and electron domain geometry:
- For three electron domains, the molecular geometry can be trigonal planar and the electron domain geometry can also be trigonal planar.
So, the molecular geometry and electron domain geometry for HCN are both trigonal planar.
It is important to note that the presence of lone pairs around the central atom can affect the bond angles, but in the case of HCN, there are no lone pairs on the central carbon atom, so the bond angles will be the idealized 120 degrees.