How to Draw the Lewis Structure for the Selenium Dioxide (SeO2) Molecule

To draw the Lewis structure for the selenium dioxide (SeO₂) molecule, follow these steps:

1. Determine the total number of valence electrons:
   • Selenium (Se) is in Group 16, so it has 6 valence electrons.
   • Oxygen (O) is also in Group 16, so each oxygen atom has 6 valence electrons.
   • Total valence electrons = 6 (Se) + 6 (O) + 6 (O) = 18 electrons.
2. Draw the skeletal structure:
   • Selenium is the central atom, and the two oxygen atoms are attached to it.
   • Structure: O-Se-O.
3. Distribute the electrons:
   • Place a single bond between Se and each O, using 4 electrons (2 bonds × 2 electrons).
   • Remaining electrons = 18 – 4 = 14 electrons.
   • Distribute the remaining electrons as lone pairs on the oxygen atoms. Each oxygen atom gets 6 electrons (3 lone pairs).
   • After placing lone pairs on oxygen, all 14 electrons are used.
4. Check the octet rule:
   • Selenium has 8 electrons around it (2 from bonds and 6 from lone pairs).
   • Each oxygen atom has 8 electrons around it (2 from bonds and 6 from lone pairs).
   • All atoms satisfy the octet rule.
5. Final Lewis structure:
   • The Lewis structure for SeO₂ shows selenium with two single bonds to oxygen atoms, and each oxygen atom has three lone pairs.

Here is the final Lewis structure for SeO₂:

    O
    ||
Se
    ||
    O