Indicate whether each of the following molecules is polar or...

Indicate whether each of the following molecules is polar or nonpolar. The molecular geometry is given in parentheses. a. $\mathrm{NF}_3$ (trigonal pyramid with N at the apex) b. $\mathrm{H}_2 \mathrm{Se}$ (angular with Se in the center position) c. $\mathrm{CS}_2$ (linear with C in the center position) d. $\mathrm{CHCl}_3$ (tetrahedral with C in the center position)

Indicate whether each of the following molecules is polar or nonpolar. The molecular geometry is given in parentheses.
a. $\mathrm{NF}_3$ (trigonal pyramid with N at the apex)
b. $\mathrm{H}_2 \mathrm{Se}$ (angular with Se in the center position)
c. $\mathrm{CS}_2$ (linear with C in the center position)
d. $\mathrm{CHCl}_3$ (tetrahedral with C in the center position)

Key Concepts

VSEPR Theory

The Valence Shell Electron Pair Repulsion (VSEPR) theory is used to predict the geometry of molecules based on the repulsion between electron pairs around a central atom. The predicted shape helps in understanding how bond dipoles might cancel or reinforce each other, thereby influencing the molecule's polarity.

Symmetry

Molecular symmetry plays a key role in determining polarity. Symmetrical molecules tend to have their individual bond dipoles cancel each other out, resulting in a nonpolar overall molecule, while asymmetric geometries often lead to a net dipole moment and hence, a polar molecule.

Molecular Geometry

Molecular geometry describes the three-dimensional arrangement of atoms in a molecule. It is crucial in determining whether the polarities of individual bonds cancel out or add together to produce an overall dipole moment. Shapes such as linear, tetrahedral, and trigonal pyramidal have different implications for cancellation of dipole vectors.

Electronegativity

Electronegativity refers to the tendency of an atom to attract electron density in a chemical bond. Differences in electronegativity between bonded atoms create polar bonds, where one end of the bond is partially negative and the other partially positive. This concept is essential when determining if individual bonds contribute to an overall molecular dipole moment.

Dipole Moment

A dipole moment is a measure of the separation of charges within a molecule, arising from differences in electronegativity and non-symmetrical shapes. The overall dipole moment of a molecule is the vector sum of its bond dipoles, and its presence indicates that the molecule is polar.

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