Multiple Choice
Which of the following statements correctly describes the Lewis dot structure of CH3CF3 (1,1,1-trifluoroethane)?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Neutral Compounds
Multiple Choice
Which of the following statements correctly describes the Lewis dot structure of the neutral compound BH2F?
A
Fluorine is the central atom, bonded to two hydrogen atoms and one boron atom.
B
Boron is the central atom, bonded to three hydrogen atoms and one fluorine atom.
C
Boron is the central atom, bonded to two hydrogen atoms and one fluorine atom, with one lone pair on boron.
D
Boron is the central atom, bonded to two hydrogen atoms and one fluorine atom, with no lone pairs on boron.
Verified step by step guidance1
Step 1: Identify the atoms involved and their typical bonding patterns. Boron (B) usually forms three bonds and has no lone pairs in neutral compounds. Hydrogen (H) forms one bond, and fluorine (F) typically forms one bond and has three lone pairs.
Step 2: Determine the central atom. The central atom is usually the least electronegative element that can form multiple bonds. Between B, H, and F, boron is the least electronegative and can form multiple bonds, so boron is the central atom.
Step 3: Arrange the atoms around the central atom. Place the two hydrogen atoms and one fluorine atom bonded to the central boron atom, making three bonds total around boron.
Step 4: Count the valence electrons to check for completeness. Boron has 3 valence electrons, each hydrogen has 1, and fluorine has 7. Total valence electrons = 3 (B) + 2×1 (H) + 7 (F) = 12 electrons. Use these electrons to form bonds and lone pairs.
Step 5: Assign lone pairs. Fluorine will have three lone pairs to complete its octet, hydrogens have none, and boron will have no lone pairs because it only forms three bonds, which is typical for boron in neutral compounds like BH2F.
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