What is the distinction between a bond dipole and a molecular dipole moment?

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The distinction between a bond dipole and a molecular dipole moment lies in their scope and focus. A bond dipole moment refers specifically to the polarity of a single chemical bond between two atoms in a molecule, primarily determined by their electronegativity difference. In contrast, a molecular dipole moment represents the overall polarity of the entire molecule, determined by summing up the individual bond dipole moments and accounting for the molecular geometry.

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1. Definition of Bond Dipole Moment

A bond dipole moment is a measure of the polarity of a chemical bond between two atoms within a molecule. It is a vector quantity, which means it has both magnitude and direction. The bond dipole moment is determined by the difference in electronegativity between the two atoms forming the bond and the distance between them. When electrons are shared unequally between atoms, it results in a polar bond, with a positive and negative end (called a dipole). The dipole moment can be represented by an arrow pointing from the positive end to the negative end (from less electronegative to more electronegative atom).
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2. Definition of Molecular Dipole Moment

A molecular dipole moment is the overall dipole moment for the entire molecule. It is a measure of the molecule's overall polarity and takes into consideration the bond dipoles of all the bonds in the molecule and the molecular geometry. To determine the molecular dipole moment, all the individual bond dipole moments in the molecule should be summed up, considering both their magnitudes and directions. The total vector sum of these bond dipoles will give the molecular dipole moment. For some molecules, bond dipoles may cancel each other due to their geometry, resulting in a nonpolar molecule with a net dipole moment of zero.
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3. Distinction between Bond Dipole and Molecular Dipole Moments

The distinction between a bond dipole and a molecular dipole moment lies in the scope and focus of the concepts. A bond dipole moment refers specifically to the polarity of a single chemical bond between two atoms in a molecule, while a molecular dipole moment represents the overall polarity of the entire molecule. In summary, - Bond dipole moment: Polarity of a single chemical bond between two atoms within a molecule, it is primarily determined by the difference in electronegativity between these two atoms. - Molecular dipole moment: Overall polarity of the whole molecule, determined by summing up the bond dipole moments of all the individual bonds while taking into account the geometry of the molecule.

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Most popular questions from this chapter

(a) The nitric oxide molecule, NO, readily loses one electron to form the \(\mathrm{NO}^{+}\) ion. Which of the following is the best explanation of why this happens: (i) Oxygen is more electronegative than nitrogen, (ii) The highest energy electron in NO lies in a \(\pi_{2 p}^{*}\) molecular orbital, or (iii) The \(\pi_{2 p}^{*}\) MO in NO is completely filled. (b) Predict the order of the \(\mathrm{N}-\mathrm{O}\) bond strengths in \(\mathrm{NO}, \mathrm{NO}^{+},\) and \(\mathrm{NO}^{-},\) and describe the magnetic properties of each.(c) With what neutral homonuclear diatomic molecules are the \(\mathrm{NO}^{+}\) and \(\mathrm{NO}^{-}\) ions isoelectronic (same number of electrons)?

The structure of borazine, \(\mathrm{B}_{3} \mathrm{N}_{3} \mathrm{H}_{6},\) is a six-membered ring of alternating \(\mathrm{B}\) and \(\mathrm{N}\) atoms. There is one \(\mathrm{H}\) atom bonded to each \(\mathrm{B}\) and to each \(\mathrm{N}\) atom. The molecule is planar. (a) Write a Lewis structure for borazine in which the formal charge on every atom is zero. (b) Write a Lewis structure for borazine in which the octet rule is satisfied for every atom. (c) What are the formal charges on the atoms in the Lewis structure from part (b)? Given the electronegativities of \(\mathrm{B}\) and \(\mathrm{N},\) do the formal charges seem favorable or unfavorable? (d)Do either of the Lewis structures in parts (a) and (b) have multiple resonance structures? (e) What are the hybridizations at the B and N atoms in the Lewis structures from parts (a) and (b)? Would you expect the molecule to be planar for both Lewis structures? (f) The six \(B-N\) bonds in the borazine molecule are all identical in length at 1.44 A. Typical values for the bond lengths of \(\mathrm{B}-\mathrm{N}\) single and double bonds are 1.51 \(\mathrm{A}\) and \(1.31 \mathrm{A},\) respectively. Does the value of the \(\mathrm{B}-\mathrm{N}\) bond length seem to favor one Lewis structure over the other? (g) How many electrons are in the \(\pi\) system of borazine?

For each statement, indicate whether it is true or false. (a) The greater the orbital overlap in a bond, the weaker the bond. (b) The greater the orbital overlap in a bond, the shorter the bond. (c) To create a hybrid orbital, you could use the sorbital on one atom with a porbital on another atom. (d) Nonbonding electron pairs cannot occupy a hybrid orbital.

Indicate whether each statement is true or false. (a) \(s\) orbitals can only make \(\sigma\) or \(\sigma^{*}\) molecular orbitals. (b) The probability is 100\(\%\) for finding an electron at the nucleus in a \(\pi^{*}\) orbital. (c) Antibonding orbitals are higher in energy than bonding orbitals (if all orbitals are created from the same atomic orbitals). (d) Electrons cannot occupy an antibonding orbital.

The phosphorus trihalides \(\left(\mathrm{PX}_{3}\right)\) show the following variation in the bond angle \(\mathrm{X}-\mathrm{P}-\mathrm{X} : \mathrm{PF}_{3}, 96.3^{\circ} ; \mathrm{PCl}_{3}, 100.3^{\circ}\) ; \(\mathrm{PBr}_{3}, 101.0^{\circ} ; \mathrm{PI}_{3}, 102.0^{\circ} .\) The trend is generally attributed to the change in the electronegativity of the halogen. (a) Assuming that all electron domains are the same size, what value of the \(X-P-X\) angle is predicted by the VSEPR model? (b) What is the general trend in the \(X-P-X\) angle as the halide electronegativity increases? (c) Using the VSEPR model, explain the observed trend in \(X-P-X\) angle as the electronegativity of \(X\) changes. (d) Based on your answer to part (c), predict the structure of \(\mathrm{PBrCl}_{4}\)

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