Multiple Choice
Which of the following best describes the Lewis dot structure for the iodide ion in nickel(III) iodide (NiI3)?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Ions
Multiple Choice
Which of the following statements correctly describes the Lewis dot structure of the AsF5 molecule?
A
Arsenic (As) is surrounded by four fluorine (F) atoms, each forming a single bond, and As has two lone pairs.
B
Arsenic (As) is surrounded by six fluorine (F) atoms, each forming a single bond, and As has no lone pairs.
C
Arsenic (As) is surrounded by five fluorine (F) atoms, each forming a double bond, and As has one lone pair.
D
Arsenic (As) is surrounded by five fluorine (F) atoms, each forming a single bond, and As has no lone pairs.
Verified step by step guidance1
Step 1: Determine the total number of valence electrons available for bonding in AsF5. Arsenic (As) is in group 15 and has 5 valence electrons, and each fluorine (F) atom is in group 17 with 7 valence electrons. Since there are 5 fluorine atoms, total valence electrons = 5 (from As) + 5 × 7 (from F) = 5 + 35 = 40 electrons.
Step 2: Draw the skeletal structure with arsenic as the central atom bonded to five fluorine atoms. Connect each fluorine atom to arsenic with a single bond. Each single bond represents 2 electrons, so 5 bonds use 10 electrons.
Step 3: Distribute the remaining electrons to complete the octets of the fluorine atoms. Each fluorine needs 8 electrons total (including bonding electrons). Since each fluorine already shares 2 electrons in the bond, assign 6 more electrons (3 lone pairs) to each fluorine atom.
Step 4: Check the electrons left after completing fluorine octets. Subtract the electrons used for bonds and fluorine lone pairs from the total valence electrons. The leftover electrons will be assigned to the central arsenic atom.
Step 5: Determine if arsenic has any lone pairs. Since arsenic can expand its octet (being in period 4), it can accommodate more than 8 electrons. In AsF5, arsenic forms five single bonds and has no lone pairs, consistent with the correct Lewis structure.
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