is SeOBr2 polar or nonpolar?
The correct answer and explanation is :
SeOBr₂ (Selenium oxybromide) is a polar molecule.
To understand why SeOBr₂ is polar, we need to consider both the molecular geometry and the distribution of electron density. Here’s the detailed explanation:
Step 1: Molecular Structure
SeOBr₂ consists of a selenium (Se) atom bonded to two oxygen (O) atoms and two bromine (Br) atoms. Selenium is in Group 16 of the periodic table, so it has six valence electrons. Oxygen and bromine each contribute one bonding electron when forming a bond with selenium. The molecular structure of SeOBr₂ can be described as having selenium at the center with two oxygen atoms and two bromine atoms arranged around it.
Step 2: Electron Pair Geometry
SeOBr₂ follows the AX₂E₂ electron pair geometry model, where:
- A represents the central atom (Se),
- X₂ represents two bonds (one to an oxygen and one to a bromine),
- E₂ represents two lone pairs of electrons on selenium.
Using the VSEPR (Valence Shell Electron Pair Repulsion) theory, the electron pairs around the central selenium atom arrange themselves to minimize repulsion, resulting in a bent or angular shape. The bond angles in SeOBr₂ are less than 120°, and the lone pairs contribute to the overall bent geometry.
Step 3: Polarity of Bonds
Each bond in SeOBr₂ has a different electronegativity:
- Oxygen is more electronegative than selenium, meaning the Se-O bond is polar, with a partial negative charge on the oxygen and a partial positive charge on the selenium.
- Bromine is less electronegative than oxygen but still more electronegative than selenium, meaning the Se-Br bonds are also polar, though less so than the Se-O bonds.
Step 4: Dipole Moment
In SeOBr₂, the molecule’s geometry is asymmetric, with the more electronegative oxygen atoms pulling electron density away from selenium more strongly than the bromine atoms. This creates a net dipole moment. The molecule does not have perfect symmetry, so the individual bond dipoles do not cancel each other out, resulting in an overall dipole moment that makes SeOBr₂ polar.
Conclusion
SeOBr₂ is polar because of its bent molecular geometry and asymmetric distribution of electronegativity, which causes an uneven sharing of electrons and a net dipole moment.