AP Chemistry
Worksheet: Ch 8-9: obj 29-34-2
Name:
Date:
1. Why must all six atoms in C2H4 be in the same plane?
2. Biacetyl and acetoin are added to margarine to make it taste more like butter.
Complete the Lewis structures, predict values for all C—C—O bond angles, and give the hybridization of the
carbon atoms in these two compounds. Are the four carbons and two oxygens in biacetyl in the same plane?
How many δ bonds and how many π bonds are there in biacetyl and acetoin?
3. One of the first drugs to be approved for use in treatment of acquired immune deficiency syndrome (AIDS)
is azidothymidine (AZT). Complete the Lewis structure for AZT.
a. How many carbon atoms are sp3 hybridized?
b. How many carbon atoms are sp2 hybridized?
c. Which atom is sp hybridized?
d. How many δ bonds are in the molecule?
e. How many π bonds are in the molecule?
f. What is the N-N-N angle in the azide (-N3) group?
g. What is the H-O-C bond angle in the side group attached to
the 5-membered ring?
h. What is the hybridization of the oxygen atom in the –CH2OH
group?
4. Hot and spicy foods contain molecules that stimulate pain-detecting nerve endings. Two such molecules are
piperine and capsaicin:
Piperine is the active compound in white and black pepper, and capsaicin is the active compound in chili
peppers. The ring structures in piperine and capsaicin are shorthand notation. Each point where lines meet
represents a carbon atom.
a. Complete the Lewis structure for piperine and capsaicin showing all lone pairs of electrons.
b. How many carbon atoms are sp, sp2, and sp3 hybridized in each molecule?
c. Which hybrid orbitals are used by the nitrogen atoms in each molecule?
d. Give approximate values for the bond angles marked a through l in the above structures.
5. All of the following statements concerning the characteristics of the halogens are true EXCEPT:
(A) The first ionization energies (potentials) decrease as the atomic numbers of the halogens increase.
(B) Fluorine is the best oxidizing agent.
(C) Fluorine atoms have the smallest radii.
(D) Iodine liberates free bromine from a solution of bromide ion.
(E) Fluorine is the most electronegative of the halogens.
6.
Which of the following molecules has the shortest bond length?
(A) N2
(C) Cl2
(E) I2
(B) O2
(D) Br2
7. The elements in which of the following have most nearly the same atomic radius?
(A) Be, B, C, N
(D) C, P, Se, I
(B) Ne, Ar, Kr, Xe
(E) Cr, Mn, Fe, Co
(C) Mg, Ca, Sr, Ba
8.
Pi (π) bonding occurs in each of the following species EXCEPT
(A) CO2
(B) C2H4
(C) CN–
(D) C6H6
(E) CH4
Ca, V, Co, Zn, As
9. Gaseous atoms of which of the elements above are paramagnetic?
(A) Ca and As only
(D) V, Co, and As only
(B) Zn and As only
(E) V, Co, and Zn only
(C) Ca, V, and Co only
10. For which of the following molecules are resonance structures necessary to describe the bonding
satisfactorily?
(A) H2S
(C) CO2
(E) PF3
(B) SO2
(D) OF2
11. The Lewis dot structure of which of the following molecules shows only one unshared pair of valence
electrons?
a. Cl2
c. NH3
e. H2O2
b. N2
d. CCl4
12. The SbCl5 molecule has trigonal bipyramid structure. Therefore, the hybridization of Sb orbitals should
be
a. sp2
c. dsp2
e. d2sp3
3
3
b. sp
d. dsp
13. Which of the following compounds is ionic and contains both sigma and pi covalent bonds?
a. Fe(OH)3
c. H2S
e. NaCN
b. HClO
d. NO2
Answers : 1. For p orbitals to line up and form pi bond, all six atoms are forced into the same plane. 2. For
biacetyl, all CCO bonds are 120° - CH3 carbons are sp3 hybridized, two central carbons are sp2 hybridized.
There are 11 sigma bonds and 2 pi bonds For acetoin, all C are sp3(109.5°) hybridized, except for the carbon
doubly bonded to the oxygen which is sp2 (120°) hybridized. There are 13 sigma bonds and one pi bond.
3a. 6 3b. 4 3c. central N of –N=N=N 3d. 33 sigma bonds 3e. 5 pi bonds 3f. 180° 3g. about 109.5° 3g.
sp3 4b. piperine 0 sp, 11 sp2, 6 sp3 carbons ; capsaicin 0 sp, 9 sp2, 9 sp3 carbons 4c. sp3 18d. a, b, c, d, g, I
and k are 120° e, f, h, j and l are 109.