Question

draw (on paper) a lewis structure for sf₆ and answer the following questions based on your drawing.

1. for the central sulfur atom:

the number of lone pairs =
the number of single bonds =
the number of double bonds =

1. the central sulfur atom

a. obeys the octet rule.
b. has an incomplete octet.
c. has an expanded octet.
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Explanation:

Question 1

Step1: Determine valence electrons

Sulfur (S) has 6 valence electrons, and each fluorine (F) has 7 valence electrons. For \( SF_6 \), total valence electrons = \( 6 + 6\times7 = 6 + 42 = 48 \).

Step2: Draw Lewis structure

Sulfur is the central atom. It forms single bonds with 6 fluorine atoms. Each single bond uses 2 electrons. So, 6 single bonds use \( 6\times2 = 12 \) electrons. Remaining electrons: \( 48 - 12 = 36 \), which are distributed as 3 lone pairs on each F (6 F atoms × 3 lone pairs × 2 electrons = 36 electrons).

• Lone pairs on central S: 0 (since all 6 valence electrons of S are used in bonding).
• Single bonds: 6 (one with each F).
• Double bonds: 0 (all bonds are single).

Question 2

The octet rule states that atoms tend to have 8 valence electrons. Sulfur in \( SF_6 \) has 12 valence electrons (6 bonds × 2 electrons from the bond, so 12 electrons around S), which is more than 8. So it has an expanded octet. Option A is wrong (doesn't obey octet rule), option B is wrong (has more than 8, not incomplete). So option C is correct.

Answer:

for Question 1:

• The number of lone pairs = \( 0 \)
• The number of single bonds = \( 6 \)
• The number of double bonds = \( 0 \)