Molecular formula FCN

Molecular formula FCN
(a) Draw the Lewis structure
(b) Formal charge of C
(c) Polar or nonpolar

The Correct Answer and Explanation is :

(a) Lewis Structure of FCN (Fluorocyanide)

To draw the Lewis structure of FCN:

1. Count Valence Electrons:

• Fluorine (F) = 7 valence electrons
• Carbon (C) = 4 valence electrons
• Nitrogen (N) = 5 valence electrons
• Total = 16 valence electrons

1. Determine Bonding:

• Carbon is the central atom (it is the least electronegative except for hydrogen).
• Carbon forms a single bond with fluorine (F) and a triple bond with nitrogen (N) to satisfy the octet rule.

1. Distribute Electrons:

• Carbon follows the octet rule with four bonds (one with fluorine, three with nitrogen).
• Nitrogen gets a lone pair to complete its octet.
• Fluorine gets three lone pairs to complete its octet.

The correct Lewis structure has F—C≡N, where:

• A single bond exists between C and F.
• A triple bond exists between C and N.
• Lone pairs are present on F and N.

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(b) Formal Charge on Carbon

The formal charge is calculated as:
[
\text{Formal Charge} = \text{Valence Electrons} – \text{Nonbonding Electrons} – \frac{\text{Bonding Electrons}}{2}
]

For Carbon (C) in FCN:

• Valence electrons: 4
• Nonbonding electrons: 0
• Bonding electrons: 8 (one single bond with F = 2, one triple bond with N = 6)
  [
  4 – 0 – \frac{8}{2} = 4 – 4 = 0
  ]
  Thus, the formal charge on Carbon is 0.

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(c) Polarity: Polar or Nonpolar?

FCN is a polar molecule.

• Reasoning:
• The molecule is linear (F—C≡N), but the atoms have different electronegativities:
  • Fluorine (F) = 3.98 (very electronegative)
  • Carbon (C) = 2.55
  • Nitrogen (N) = 3.04
• The C–F bond is highly polar, pulling electrons towards fluorine.
• The C≡N bond is also polar, but less so than C–F.
• Since fluorine is much more electronegative than nitrogen, the molecule has a net dipole moment, making it polar.

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Conclusion

• Lewis Structure: F—C≡N
• Formal Charge of Carbon: 0
• Polarity: Polar molecule due to electronegativity differences and molecular dipole.

Now, I’ll generate the image of the Lewis structure for FCN.

Here is the Lewis structure diagram for the FCN (fluorocyanide) molecule. Let me know if you need any modifications or further explanations!