What is the polarity of OBr2 molecule? (Hint: first draw a Lewis structure and then decide on polarity) hydrogen bond. polar molecule_ non-polar molecule ionic: Br2
The Correct Answer and Explanation is:
To determine the polarity of an OBr2 (dibromine monoxide) molecule, we need to consider its Lewis structure, the arrangement of the atoms, and the electronegativity differences between the atoms involved. Here’s how we can break it down:
Step 1: Drawing the Lewis Structure of OBr2
- Count the valence electrons:
- Oxygen (O) has 6 valence electrons.
- Each bromine (Br) has 7 valence electrons.
- Total valence electrons = 6 (O) + 2 * 7 (Br) = 20 valence electrons.
- Arrange the atoms:
- Oxygen (being more electronegative) will be the central atom, and two bromine atoms will be bonded to it.
- Draw the bonds:
- Place single bonds between oxygen and each bromine atom.
- Distribute the remaining electrons:
- After placing the bonding pairs, place the remaining electrons as lone pairs on the oxygen and bromine atoms. Oxygen will have two lone pairs, and each bromine will have three lone pairs.
This gives us the Lewis structure of OBr2, where the oxygen atom is in the center, bonded to two bromine atoms.
Step 2: Molecular Geometry
The electron pair geometry around the central oxygen atom is trigonal planar, but because there are lone pairs of electrons on oxygen, the molecular shape will be bent or V-shaped (similar to the H2O molecule).
Step 3: Electronegativity and Dipoles
- Electronegativity of oxygen: 3.44
- Electronegativity of bromine: 2.96
The difference in electronegativity between oxygen and bromine creates a polar covalent bond. The oxygen atom is slightly more electronegative than the bromine atoms, so it pulls electron density towards itself, creating a partial negative charge (δ-) on oxygen and partial positive charges (δ+) on the bromines.
Step 4: Net Dipole Moment
Since the molecule is bent, the individual bond dipoles do not cancel each other out. Therefore, there is a net dipole moment that points towards the oxygen atom, making OBr2 a polar molecule.
Conclusion
OBr2 is a polar molecule because it has a net dipole moment due to the asymmetrical shape and the difference in electronegativity between oxygen and bromine.
Summary:
- Bond type: Polar covalent
- Molecular shape: Bent
- Polarity: Polar molecule
- Hydrogen bond: Not applicable (there are no hydrogen atoms present)
- Ionic: Not ionic because the bond between oxygen and bromine is covalent, not ionic.
