Understanding the Context

NF₃ is a fluorine tri-hydride compound in which neon (Ne) forms three single bonds with fluorine (F) atoms, leaving the neon atom with a complete octet despite its position in the second period (which usually lacks expanded octets). While limited by neon’s stable noble gas configuration, NF₃ serves as a useful model for studying hypervalent compound theory and electron-pair repulsion.

Building the Lewis Structure of NF₃

Step 1: Count Valence Electrons

• Neon (Ne) has 8 valence electrons.
  
• Each fluorine (F) contributes 7 valence electrons.
  
• Total valence electrons = 8 + (3 × 7) = 29 electrons

Key Insights

Step 2: Draw a Skeletal Structure

Place the central neon atom bonded to three fluorine atoms. Neon is less likely to form expanded octets compared to heavier halogens, but to accommodate three bonds, we draw:

F — Ne — F
|
F

However, in reality, the neutral NF₃ structure features one lone pair on neon.

Step 3: Distribute Electrons

Final Thoughts

Neon forms three single bonds (each bond = 2 electrons → 6 total bonding electrons), accounting for 6 electrons.

Remaining electrons: 29 – 6 = 23 electrons

Place these as lone pairs on the fluorine atoms first:

• Each F needs 6 more electrons (3 lone pairs) to complete its octet.
  
• 3 fluorines × 6 = 18 electrons used.
  
• Remaining electrons: 23 – 18 = 5 electrons

Now assign the remaining 5 electrons to neon as a lone pair (1 lone pair = 2 electrons), plus 3 unpaired electrons (hydride-like instability), though in practice neon uses a lone pair for stability.

Final electron distribution: