Draw the Lewis Structure of SeS2
The correct answer and explanation is :
Lewis Structure of Selenium Disulfide (SeS₂)
Step 1: Determine the Total Valence Electrons
- Selenium (Se) is in Group 16 and has 6 valence electrons.
- Sulfur (S) is also in Group 16 and each sulfur atom has 6 valence electrons.
- Total valence electrons = 6 (Se) + 6 (S) + 6 (S) = 18 electrons.
Step 2: Determine the Central Atom
- Selenium is less electronegative than sulfur, so Se is the central atom, with the two sulfur atoms surrounding it.
Step 3: Connect the Atoms with Single Bonds
- We start by forming single bonds between Se and each S. Each single bond contains 2 electrons.
- Using 4 electrons for bonds, we have 18 – 4 = 14 electrons remaining.
Step 4: Distribute Remaining Electrons
- First, we complete the octets of the outer atoms (sulfur atoms).
- Each sulfur atom needs 8 electrons in total (including bonding pairs), so we place 6 non-bonding electrons (three lone pairs) on each sulfur.
- Now, all 14 electrons are used (6 on each S and 2 in the Se–S bonds).
Step 5: Check the Central Atom’s Octet
- Selenium has only 4 valence electrons (from the single bonds), which is not a full octet.
- To satisfy the octet rule, each sulfur atom shares an extra lone pair with selenium, forming two double bonds (Se=S).
- Now, selenium has 8 valence electrons (two double bonds), fulfilling its octet.
Final Lewis Structure
:S:: :S:
|| ||
Se- Bond Type: Two double bonds (Se=S).
- Lone Pairs: Each S has 2 lone pairs, while Se has no lone pairs.
Explanation
- Molecular Shape: Linear (AX₂ type, 180° bond angle) based on VSEPR theory.
- Polarity: Nonpolar, since the molecular shape is symmetrical and dipole moments cancel out.
- Resonance: No resonance as Se=S bonds are stable.
This structure satisfies the octet rule and minimizes formal charges, making it the most stable Lewis structure for SeS₂.