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Drawing a New Bond From a Lone Pair 4 questions
Drawing a New Bond From a Lone Pair
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A molecular display compares ammonia, NH3, with boron trifluoride, BF3. In the model the nitrogen in NH3 has three N–H bonds and one lone pair. The boron in BF3 has three B–F bonds and room for another shared pair. The display can use the nitrogen lone pair to form a new bond to boron. No atoms or electrons leave.
| Center | Atoms bonded before the change | Lone pairs before the change |
|---|---|---|
| N | 3 H | 1 |
| B | 3 F | 0 |
Question 1
Which pair of atoms becomes newly connected in the model?
- H and F
- N and F
- N and B
- B and H
Question 2
Draw the product connections. Show the N–B bond and keep the three H atoms attached to N and the three F atoms attached to B.
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The display uses this shape rule for the boron center: three bonded neighbors give a flat arrangement, while four give an arrangement that extends out of that plane.
Question 3
Use the new neighbor count to explain why the boron center no longer fits the original flat model.
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Question 4
A student says that if nitrogen loses its lone pair, the full product must have lost two electrons. Evaluate the claim using the electron-pair model.
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