Triad 3 Test Study
Guide Key
West Valley High School
AP Chemistry
Mr. Mata
Chapter 7
1. How many electrons in an atom can have n = 5, l
= 3?
Answer: l = 3 (5f) = 14 e-
Chapter 7
2. Which of these elements would have the
highest first ionization energy?
Answer: C. Flourine (1681 J/mol)
far right corner; highest EN value
Chapter 7
3. Which of the following combinations of quantum
numbers is not allowed?
Answer: D: n = 1, l = 0, m(l) = 1, m(s) = ½
m(l) cannot be greater than l
Chapter 7
4. Each electron in an atom has a unique set of
four quantum numbers. This observation is
credited to:
Answer: A. Pauli
Chapter 7
5. An element having the configuration [Xe]6s1
belongs to the Group:
Answer: E. alkali metals (group 1 Cs = 6s1)
Chapter 7
6. Which of the following atoms would experience
the greatest energy loss when gaining an
electron?
Answer: D. Cl (highest EN value)
Chapter 7
7. Of the following elements, which one is most
likely to form an ion through the loss of two
electrons?
Answer: B. strontium (group 2; 2 valence e-’s)
Chapter 7
8. A photon has a frequency is 3.90 x 1014 Hz?
What is the energy of the photon?
Answer:
E = hv = (6.62 x 10 -34 J/s)(3.90 x 10 14 Hz)
E = 2.60 x 10 -20 J
Chapter 7
9. An element Z has the configuration [Xe]6s2. The
oxide of this element will have the formula:
Answer: A. ZO
Z = group 2 (+2 ion)
Oxide = group 16 (-2 ion)
Chapter 7
10. What is the wavelength of a photon whose
frequency is 3.90 x 1014 Hz?
Answer:
Wavelength = c/v
= 2.9979 x 10 8 m/s
3.90 x 10 14 s -1
= 7.69 x 10 -7 m = 769 nm
Chapter 8
1. Which of the following molecules has a dipole
moment?
Answer: D. H2O
Chapter 8
2. Given the following bond energies, estimate the
enthalpy change (heat of reaction) for the
combustion of methane (CH4).
Answer:
CH4 + 2O2  CO2 + 2H2O
CH4: 4 mol C-H x 413 kJ/ 1 mol = 1652 kJ (react)
2O2: 2 mol O=O x 495 kJ/ 1 mol = 990 kJ (react)
CO2: 2 mol C=O x 799 kJ/1 mol = 1598 kJ (prod)
2H2O: 4 mol H-O x 463 kJ/1 mol = 1852 kJ(prod)
∆ H = react (break bonds) – products (form bonds)
∆ H = 2642 kJ – 3450 kJ = - 808 kJ
Chapter 8
3. Draw the Lewis structure for hydrogen cyanide
(HCN):
Answer:
H–C=N:
Chapter 8
4. Which of the following compounds is most likely
to be ionic?
Answer: A. MgCl2 (EN values 1.2 – 3.0 = 1.8)
Chapter 8
5. Which of these Lewis structures is invalid?
Answer: E.
Chapter 8
6. In the Lewis structure for CH2Cl2, the number of
unshared electron pairs is:
Answer: C. 6 (each Cl w/3 pairs of unshared e-’s
Chapter 8
7. In the Lewis structure for CH2Cl2, the central
atom shares ___ electrons.
Answer: D. 8
Chapter 8
8. In which of the following compounds does the
bond between the central atom and chlorine
have the greatest ionic character?
Answer: C. CaCl2 (largest EN diff; ionic)
Chapter 8
9. Which of the following molecules must contain
at least one double bond
Answer: A. CH3COOH
Chapter 8
10. How many unshared electron pairs must be
included in the Lewis structure for water, H2O?
Answer: A. 2
Chapter 9
1. How many electrons are involved in pi (p)
bonding in a molecule of ethyne (acetylene) C2H2?
Answer: E. four
Chapter 9
2. Hybridization of carbon in the molecule CH2O is
in what form?
Answer: sp2
H
H
C=O
Chapter 9
3. Double bonds can be thought of as consisting
of:
Answer: E. A sigma (s) bond and a pi (p) bond
Chapter 9
4. How many sigma (s) bonds and pi (p) bonds
are present in the molecule depicted above?
Answer: 3 sigma; 1 pi
Chapter 9
5. How many sigma (s) bonds and pi (p) bonds
are present in the molecule depicted above?
Answer: sp2
Chapter 9
6. How manysigma (s) bonds and pi (p) bonds
are present in one molecule of napthalene?
Answer: 19 sigma; 5 pi
Chapter 9
7. The geometry associated with sp2 hybridization
is:
Answer: trigonal planar
Chapter 9
8. What is the hybridization of the carbon in
CO2?
Answer: sp