Question

molecule proposed lewis structure is this a reasonable structure? if not, why not? sf₃⁻ yes, its a reasonable structure. no, the total number of valence electrons is wrong. the correct number is: no, some atoms have the wrong number of electrons around them. the symbols of the problem atoms are:

Explanation:

Step1: Determine valence electrons of each atom

Sulfur (S) has 6 valence electrons, Fluorine (F) has 7 valence electrons each, and there is a -1 charge (which adds 1 valence electron).

Step2: Calculate total valence electrons

For \( SF_3^- \), number of F atoms is 3. So total valence electrons = valence electrons of S + 3×valence electrons of F + 1 (for -1 charge) = \( 6 + 3\times7 + 1 \) = \( 6 + 21 + 1 = 28 \).
Now, let's check the proposed Lewis structure: In the given structure, let's count the electrons. Each F has 6 non - bonding electrons (3 lone pairs) and 2 bonding electrons (1 bond), so each F has \( 6 + 2 = 8 \) electrons. S has 2 double bonds (4 bonding electrons) and 2 single bonds (2 bonding electrons), and let's see the lone pairs? Wait, maybe a better way: count the total electrons in the structure. The given structure: each F has 3 lone pairs (6 electrons) and 1 bond (2 electrons), so 8 per F. S has a double bond (4 electrons) and two single bonds (2 electrons each, so 4 electrons), so total bonding electrons for S: 8, and does it have lone pairs? Wait, maybe the error is in total valence electrons. Let's recalculate the total valence electrons for the proposed structure. Let's count the electrons: The structure has 3 F atoms, each with 6 non - bonding electrons (3 lone pairs) and 1 bond (2 electrons), so per F: 8, 3 F: 24. S has a double bond (4 electrons) and two single bonds (2 electrons each, so 4 electrons), so S has 8 bonding electrons, and no non - bonding? Wait, no, the total electrons in the structure: the brackets with a -1 charge. Let's count all electrons: Each F: 6 non - bonding (3 pairs) + 2 bonding = 8. Three F: 3×8 = 24. S: double bond (4) + two single bonds (4) = 8. Then total electrons: 24+8 = 32? Wait, no, maybe I made a mistake. Wait, the formula for calculating total valence electrons for a Lewis structure: sum of valence electrons of all atoms plus/minus charge. For \( SF_3^- \), S (6) + 3F (7 each) + 1 (for -1) = 6 + 21+1 = 28. Now, let's count the electrons in the proposed structure. Let's look at the given Lewis structure: Each F has 3 lone pairs (6 electrons) and 1 bond (2 electrons), so 8 per F. There are 3 Fs: 3×8 = 24. S has a double bond (4 electrons) and two single bonds (2 electrons each, so 4 electrons), so S has 8 bonding electrons. Also, is there a lone pair on S? Wait, the structure as drawn: the S has a double bond and two single bonds, and the Fs have 3 lone pairs each. Let's count all the electrons: non - bonding electrons: each F has 6, 3 Fs: 18. Bonding electrons: the double bond (4) and two single bonds (2 each, so 4), total bonding electrons: 8. So total electrons: 18+8 = 26, plus the -1 charge? Wait, no, the charge is part of the ion. Wait, maybe the error is in the total number of valence electrons. The correct total is 28, and the proposed structure has a wrong total. So the answer to the first part (if not, why not) is "No, the total number of valence electrons is wrong." and the correct number is 28.

Answer:

No, the total number of valence electrons is wrong.
The correct number is: 28