Extra Unit 6 Problems for the Web Page: Chemical
Bonding and Molecular Geometry. (See Ms Fed to check Lewis
structures)
1. Write the Lewis structures for the following : (a) HOCl (b) NH4Cl (c) SiH4
(d) BH4- (e) H2CO
2. Which of the following is most likely to be an ionic compound? P2O5, SbCl5,
H2Te, SrCl2 [SrCl2]
3. Which of the following compounds has a double bond? N2, SO2, Cl2, NH4+,
SO4-2 [SO2]
4. Draw the Lewis structures for CO, CO2, and CO3-2, and predict the trend in
CO bond distances. [CO3-2 < CO2 <CO]
5. Explain why NH3 is a polar molecule, whereas BH3 is non-polar. [pyramidal
vs planar]
6. For each of the following statements, write the number preceding the bond or
binding forces, chosen from the list below, which is most closely associated
with that statement.
Bonds or Binding Forces: 1. Ionic bonds 2. Network bonds 3. Coordinate
covalent bonds 4. Hydrogen bonds. 5. Metallic bonds 6. Van der Waals forces
7. Triple covalent bonds
a) A proton combines with water to form a hydronium ion b) Mobility of
valence electrons results in good electrical conductivity in the solid phase. c)
Non-conductors in the solid phase become electrical conductors in the liquid
phase. d) Solid iodine sublimes readily upon heating. e) The boiling point of
hydrogen fluoride is much higher than that of HCl, HBr, ot HI. [3,5,1,6,4]
The following problems are for Honors only:
11. From experiments it is known that the S-O bonds in SO2 are equivalent.
Draw Lewis structures to explain. [resonance structures]
12. Write the Lewis structures for BI3 , PF5, HCCCH3, HN3, and NO.
13. How many electrons occupy p orbitals in (a) CO2 (b) HCN [4, 4]
14. In which of the following molecules would you expect the central atom to
use sp3d2? PF5, BrF5, CO2, SiO2, PtCl4-2 [BrF5]
15. Which types of hybrid orbitals on a central atom in a molecule give the
following angles between atoms bonded to the central atom? (a) 180 0 (b) 1200
(c) 900 (planar structure) (d) 900 (octahedral structure) [sp, sp2, sp2d, sp3d2]
The following is an example of an Honors test for the Bonding unit:
Multiple Choice:
1. How many unpaired electrons are in the Lewis electron dot symbol for an
aluminum atom?
a) 0 b) 1 c) 3 d) 4
2. Which one of the following is the correct Lewis electron dot formula for
CO3-2 ? (get diagram from Ms Fed)
3. Which one of the following species violates the octet rule?
a) NI3 b) SO2 c) ICl5 d) SiF4
4. What is the shape of the of the PF4+ ion?
a) octahedral b) trigonal bipyramid c) tetrahedral d) bent (angular)
5. The bond angles a, b, and c in the molecule shown below would respectively
be (get diagram from Ms Fed)
a) 109.5o , 109.5o , 109.5o b) 120o , 109.5o ,120o c) 107o , 109.5o , 120o d) 90o ,
180o, 90o
6. How many pi bonds are in the molecule shown below? (get diagram from
Ms Fed)
a) 0 b) 1 c) 2 d) 4
7. The AsF6- ion is octahedral. The hybrid orbitals used by the As atom for the
bonding are
a) sp2d2 b) sp3 c) sp3d d) sp3d2
8. Which of the following does not influence the electronegativity of an
element?
a) the size of the atom b) the shielding effect of the electrons c) the number of
protons in the nucleus d) the number of neutrons in the nucleus
9. If there are only two pairs of electrons in the outer energy level of an atom in
a molecule they will be found
a) at 90o to one another b) on the same side of the nucleus c) at 120o to one
another d) on opposite sides of the nucleus
10. Which of the following molecules is bent?
a) SF2 b) SiCl4 c) PH3 d) NCl3
11. Beryllium fluoride has a linear structure. This indicates that the
hybridization of beryllium is
a) sp b) sp2 c) sp3 d) no hybridization
12. In a comparison of the repulsion between pairs of electrons, which of the
following lists the repulsion strength from the greatest to the least?
a) bonded/bonded , bonded/unbonded , unbonded/unbonded b)
bonded/unbonded , bonded/bonded , unbonded/unbonded c)
unbonded/unbonded , bonded/unbonded , bonded/bonded d)
unbonded/unbonded , bonded/bonded , bonded/unbonded
13. How does calcium obey the octet rule when reacting to form compounds?
a) it gains electrons b) it gives up electrons c) it does not change its number of
electrons
14. Under what conditions can potassium bromide conduct electricity?
a) only when melted b) only when dissolved c) only when it is in crystal form
d) only when melted or dissolved in water
15. Which of these elements does not exist as a diatomic molecule?
a) Ne b) F c) H d) I
16. When one atom contributes both bonding electrons in a single covalent
bond, the bond is called a(n)
a) unequal covalent bond b) coordinate covalent bond c) ionic covalent bond d)
ordinary covalent bond
17. A bond that is symmetrical along the axis between two atomic nuclei is a(n)
a) alpha bond b) pi bond c) beta bond d) sigma bond
18. Which of the following structures is characterized by a bond angle of 107o ?
a) tetrahedron b) angular c) pyramid d) linear
19. In an electric field, which region of the water molecule is attracted to the
positve pole?
a) the oxygen region b) the hydrogen region c) no part of the water molecule is
attracted?
20. What causes hydrogen bonding?
a) attraction between ions b) motion of electrons c) sharing of electron pairs d)
bonding of a covalently bonded hydrogen to an unshared electron pair
Problems:
21. Draw an electron dot diagram for each of the following covalent molecules:
a) BeAt2 b) HSiN c) AlCl4- d) SOCl2
22. Using the type of intermolecular bonds, explain the following:
a) H2O has a higher boiling point than H2Se
b) BCl3 has a lower melting point than BBr3
c) BF3 does not dissolve in water while SF2 is very soluble in water
d) GeO2 has a high melting point and does not conduct electricity when placed
on water, while CaBr2 has a high melting point but does conduct electricity
when placed in water.
23. Predict (a) the bond type (s-s , s-p , etc), (b) bond angle and (c) shape of the
molecules formed when the following elements combine:
i) Fluorine (F) and Tellurium (Te)
ii) Arsenic (As) and Hydrogen (H)
iii) Beryllium (Be) and Iodine (I)
24. Use the following clues to determine which one substance from the
following list is being described. Circle your choice.
CS2 , HF , SiO2 , I2 , KCl , Ag
a) at room temperature, the solid state of this substance is brittle and can shatter
if struck by a hammer b) it has a very high melting point c) it is insoluble in
CCl4 d) as a solid, it does not conduct electricity e) it dissolves well in liquid
NH3 and water
25. Identify the hybridization type on all atoms in the following compounds:
a) ClO3- b) SO2 c) NO2+
Answers: 1 c, 2 a, 3 c, 4 c, 5 c, 6 c, 7 d, 8 d, 9 d, 10 a, 11 a, 12 c, 13 b, 14 d,
15 a, 16 b, 17 d, 18 c, 19 a, 20 d, 21 check your answers with Ms Fed. 22 a)
water has hydrogen bonding b) boron tribromide has a higher molecular
mass c) boron trifluoride is trigonal planar and therefore nonpolar; sulfur
difluoride is angular and therefore polar d) germanium dioxide is a
network solid; calcium bromide is ionic . 23 i)sp3-sp3; 104.5o; angular ii)
sp3-s; 107o; pyramidal iii) sp-sp3; 180o; linear . 24 KCl, 25 a) sp3 on all
atoms , b) sp2 on the sulfur and the oxygen with the double bond; sp3 on the
other oxygen , c) sp on the nitrogen; sp2 on each oxygen