Is SF
a polar or non-polar molecule? You must justify your answer to receive credit.
The Correct Answer and Explanation is:
Correct Answer:
SF₄ (sulfur tetrafluoride) is a polar molecule.
Explanation:
SF₄ has a seesaw molecular geometry. This shape arises because the sulfur atom in SF₄ has five regions of electron density around it: four bonding pairs (to fluorine atoms) and one lone pair. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, these five regions arrange themselves into a trigonal bipyramidal electron geometry to minimize repulsion. In this arrangement, the lone pair occupies an equatorial position to reduce repulsion with bonding pairs.
The resulting molecular shape is a seesaw, which is asymmetrical. This geometry causes an uneven distribution of charge across the molecule. The fluorine atoms are highly electronegative and pull electron density toward themselves. However, because the molecule is not symmetrical, the individual bond dipoles do not cancel out.
In a symmetrical molecule like CF₄ or SF₆, the dipoles would cancel because they are arranged evenly in three-dimensional space. But in SF₄, the presence of a lone pair and the resulting shape lead to a net dipole moment, meaning there is an overall direction to the electron pull in the molecule.
This net dipole moment makes SF₄ polar. Polar molecules tend to have partial positive and partial negative regions, leading to dipole-dipole interactions in a substance. This influences properties such as boiling point, solubility, and reactivity.
In summary, SF₄ is a polar molecule because its seesaw shape results in an unequal distribution of electron density and a net dipole moment that does not cancel out.
