is SeH2 polar or non polar?
The correct answer and explanation is :
SeH₂ (Selenium Hydride) is a polar molecule.
Explanation:
To determine whether SeH₂ is polar or non-polar, we must consider the molecule’s molecular geometry, electronegativity differences, and dipole moment.
- Electronegativity:
- Selenium (Se) is less electronegative than hydrogen (H). The electronegativity of Se is 2.55, while that of hydrogen is 2.20. This difference creates a polar covalent bond between selenium and hydrogen, with the selenium atom slightly negative (δ-) and the hydrogen atoms slightly positive (δ+).
- Molecular Geometry:
- SeH₂ has a bent or V-shaped structure similar to H₂O. This is due to the presence of lone pairs of electrons on the selenium atom. Selenium, like oxygen in water, has two lone pairs of electrons, which result in a bent molecular geometry according to the VSEPR theory (Valence Shell Electron Pair Repulsion).
- In a bent structure, the bond dipoles do not cancel each other out, as they would in a linear structure. Instead, they add up to create a net dipole moment pointing from the hydrogen atoms toward the selenium atom.
- Dipole Moment:
- Since SeH₂ has a bent geometry and polar bonds, the individual bond dipoles do not cancel each other. The molecule has an overall dipole moment, which indicates that SeH₂ is polar.
In contrast, molecules with symmetrical structures where dipoles cancel each other out (e.g., CO₂) are non-polar. However, in SeH₂, the bent geometry prevents such cancellation, making the molecule polar.
Conclusion:
SeH₂ is polar because of its bent molecular geometry and the difference in electronegativity between selenium and hydrogen, which results in a net dipole moment.