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- Sodium azide is a shock-sensitive compound that releases N2 upon physical impact. The compound is used in automobile airbags. The azide ion is N3-. (a) Draw the Lewis structure of the azide ion that minimizes the formal charge (it does not form a triangle). Is it linear or bent?
Problem 1
Problem 3a
For each molecule (a)–(f), indicate how many different electron-domain geometries are consistent with the molecular geometry shown. a.
Problem 4c
The molecule shown here is difluoromethane 1CH2F22, which is used as a refrigerant called R-32. (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?
Problem 5c
The following plot shows the potential energy of two Cl atoms as a function of the distance between them. (c) If the Cl2 molecule is compressed under higher and higher pressure, does the Cl–Cl bond become stronger or weaker?
Problem 6a
The orbital diagram that follows presents the final step in the formation of hybrid orbitals by a silicon atom. (a) Which of the following best describes what took place before the step pictured in the diagram: (i) Two 3p electrons became unpaired, (ii) An electron was promoted from the 2p orbital to the 3s orbital, or (iii) An electron was promoted from the 3s orbital to the 3p orbital?
Problem 6b
The orbital diagram that follows presents the final step in the formation of hybrid orbitals by a silicon atom. (b) What type of hybrid orbital is produced in this hybridization?
Problem 7a
In the hydrocarbon
(a) What is the hybridization at each carbon atom in the molecule?
Problem 7b
In the hydrocarbon (b) How many s bonds are there in the molecule?
Problem 7d
In the hydrocarbon
(d) Identify all the 120° bond angles in the molecule.
Problem 8a
The drawing below shows the overlap of two hybrid orbitals to form a bond in a hydrocarbon. (a) Which of the following types of bonds is being formed: (i) C¬C s, (ii) C¬C p, or (iii) C¬H s?
Problem 8b
The drawing below shows the overlap of two hybrid orbitals to form a bond in a hydrocarbon. (b) Which of the following could be the identity of the hydrocarbon: (i) CH4, (ii) C2H6, (iii) C2H4, or (iv) C2H2?
Problem 9e
The molecule shown below is called furan. It is represented in typical shorthand way for organic molecules, with hydrogen atoms not shown, and each of the 4 vertices representing a carbon atom.
(e) The C¬C¬C bond angles in furan are much smaller than those in benzene. The likely reason is which of the following: (i) The hybridization of the carbon atoms in furan is different from that in benzene, (ii) Furan does not have another resonance structure equivalent to the one above, or (iii) The atoms in a five-membered ring are forced to adopt smaller angles than in a six-membered ring.
Problem 10a
The following is part of a molecular orbital energy-level diagram for MOs constructed from 1s atomic orbitals.
(a) What labels do we use for the two MOs shown?
Problem 11a1
For each of these contour representations of molecular orbitals, identify (a) the atomic orbitals (s or p) used to construct the MO (i)
Problem 11a3
For each of these contour representations of molecular orbitals, identify (a) the atomic orbitals (s or p) used to construct the MO (iii)
Problem 11b3
For each of these contour representations of molecular orbitals, identify (b) the type of MO (s or p) (iii)
Problem 11b1
For each of these contour representations of molecular orbitals, identify (b) the type of MO (s or p) (i)
Problem 11c1
For each of these contour representations of molecular orbitals, identify (c) whether the MO is bonding or antibonding (i)
Problem 13a
(a) An AB2 molecule is linear. How many nonbonding electron pairs are around the A atom from this information?
Problem 13b
(b) How many nonbonding electrons surround the Xe in XeF2?
Problem 13c
(c) Is XeF2 linear
Problem 14a
(a) Boron trichloride 1BCl32 and the carbonate ion 1CO3 2- 2 are both described as trigonal. What does this indicate about their bond angles?
Problem 14b
(b) The PCl3 molecule is trigonal pyramidal, while ICl3 is T-shaped. Which of these molecules is flat?
- How does a trigonal pyramid differ from a tetrahedron so far as molecular geometry is concerned?
Problem 15
Problem 16
Describe the bond angles to be found in each of the following molecular structures: (a) trigonal planar, (b) tetrahedral, (c) octahedral, (d) linear.
Problem 17b
(b) An AB4 molecule has two lone pairs of electrons on the A atom (in addition to the four B atoms). What is the electron-domain geometry around the A atom?
Problem 18
Would you expect the nonbonding electron-pair domain in NCl3 to be greater or smaller in size than the corresponding one in PCl3?
- In which of these molecules or ions does the presence of nonbonding electron pairs produce an effect on the molecular shape? (a) CO2, (b) CH2Br2, (c) OF2, (d) BCl3, (e) SF6.
Problem 19
Problem 20
In which of the following molecules can you confidently predict the bond angles about the central atom, and for which would you be a bit uncertain? Explain in each case. (a) H2S, (b) BCl3, (c) CH3I, (d) CBr4, (e) TeBr4.
Problem 21a
How many nonbonding electron pairs are there in each of the following molecules: (a) (CH3)2S
