How do you draw the Lewis structure of BF₃?

BF₃ has 24 valence electrons. Boron is central, bonded to three fluorines. Three single bonds use 6 electrons; 18 remain. 18 electrons go to the three F atoms as 3 lone pairs each (6 e⁻ × 3 = 18), completing their octets.

Lewis Structure of BF₃ (Boron Trifluoride)

What is the Lewis structure of BF₃?

BF₃ has 24 valence electrons, 3 bonding electron pairs, and 9 lone pairs. BF₃ has 24 valence electrons. Three B–F single bonds use 6 electrons, and each F has 3 lone pairs (18 e⁻). Boron has only 6 electrons — an incomplete octet. This makes BF₃ a strong Lewis acid.

Lewis structure of BF₃ (Boron Trifluoride)

Formula	BF₃
Name	Boron Trifluoride
Total Valence Electrons	24
Lone Pairs	9
Has Resonance	No
Concept	Electron Deficient
Difficulty	Advanced

Step 1: Count Valence Electrons

B (Group 3A) has 3, each F has 7: 3 + 3(7) = 24 total.

Step 2: Draw the Skeleton

Boron is central, bonded to three fluorines. Three single bonds use 6 electrons; 18 remain.

Step 3: Distribute Lone Pairs

18 electrons go to the three F atoms as 3 lone pairs each (6 e⁻ × 3 = 18), completing their octets.

Step 4: Form Multiple Bonds

Boron only has 6 electrons from its 3 bonds — but that is acceptable! B is electron-deficient and does NOT need an octet. This is one of the few exceptions to the octet rule.

Step 5: Check Formal Charges

B: FC = 3 - 0 - ½(6) = 0
F: FC = 7 - 6 - ½(2) = 0
The incomplete octet on B makes BF₃ a powerful Lewis acid.

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