The molecule shown here is difluoromethane (CH2 F2), which is used as a refrigerant called R-32

step 1 So from the Lewis structure here, we can see that there are four different single bonds or four

The molecule shown here is difluoromethane (CH2 F2), which...

The molecule shown here is difluoromethane $\left(\mathrm{CH}_{2} \mathrm{~F}_{2}\right)$, which is used as a refrigerant called $R-32$. (a) Based on the structure, how many electron domains surround the $\mathrm{C}$ atom in this molecule? (b) Would the molecule have a nonzero dipole moment? (c) If the molecule is polar, which of the following describes the direction of the overall dipole moment vector in the molecule: (i) from the carbon atom toward a fluorine atom, (ii) from the carbon atom to a point midway between the fluorine atoms, (iii) from the carbon atom to a point midway between the hydrogen atoms, or (iv) From the carbon atom toward a hydrogen atom? [Sections $9.2$ and 9.3]

Key Concepts

Electronegativity and Bond Polarity

Electronegativity is a measure of an atom's ability to attract and hold electrons in a chemical bond. When atoms with differing electronegativities form a bond, the result is a bond dipole, as electrons are drawn more toward the more electronegative atom. This difference in electron distribution is foundational to understanding the creation of individual bond dipoles, which combine to give the overall molecular dipole moment.

Molecular Polarity and Dipole Moment

Molecular polarity arises when there is an uneven distribution of electron density in a molecule, typically due to differences in electronegativity between atoms. The dipole moment is a vector quantity that indicates the direction and magnitude of this charge separation; its overall value depends on how individual bond dipoles add together in three-dimensional space.

Electron Domains

This concept refers to the regions around a central atom where electrons are localized, including bonding pairs and lone pairs. Counting electron domains is essential to determine the electron-domain geometry of a molecule, which in turn aids in understanding the molecular structure and predicting properties such as bond angles and molecular polarity.

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) theory is used to predict the shape of molecules based on the repulsion between electron domains (bonding and lone pairs) around a central atom. By considering the number and arrangement of these electron domains, one can predict the three-dimensional geometry of a molecule, which is critical for understanding both its physical and chemical behavior.

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