At this stage, Selenium only has 6 electrons (two bonds and one lone pair). To satisfy the octet rule for the central atom, move a lone pair from one of the oxygen atoms to form a double bond with Selenium. Resonance and Formal Charge

The Lewis structure of SeO42- (selenate ion) consists of:

At this point, every oxygen has an octet. But selenium currently has only 8 electrons around it (4 bonds), which is an octet as well. However, Se is in period 4 and can expand its octet due to available d-orbitals.

Using the single-bond structure (all Se–O single bonds, each O with 3 lone pairs):

In the world of chemistry, visualizing how atoms connect is the first step toward understanding how substances behave. If you are looking into the , you are likely exploring the bonding characteristics of Selenium Dioxide (SeO₂) .

If Se has two double bonds (each double bond = 4 e⁻ counted in bonding) and two single bonds (each single bond = 2 e⁻), total bonding electrons around Se = 2×4 + 2×2 = 12 e⁻. So FC(Se) = 6 – 0 – (12/2) = 6 – 6 = .