CHEMISTRY 1031 SPRING 2017, EXAM III
Problem A: Use the plot below to answer the following questions:
(a) What should the x-axis be labeled? radius
(b) What should the y-axis be labeled? total radial probability
(c) Which curve represents an orbital where electrons can penetrate? B
(d) Which curve represents an orbital that contains a node? B
(e) What orbital does curve A represent? 1s
Problem B (9 Points): Please answer the following question about chromium:
(a) What is the electron configuration of Cr in the ground state?
(b) How many valence electrons does Cr have?
(c) Place the valence electrons in an orbital diagram. Describe why you
filled the orbital diagram the way you did.
(A) 1s22s22p63s23p64s13d5
(B) 6 valence electrons
(C) 1 electron in 4s and 1 electron in each orbital of 3d, all spin up. More stability by having s
and d all half filled
1. What is the speed of an electron with a wavelength of 425 nm?
A) 1000 m/s
B) 1.7 x 10-6 m/s
C) 7.05 x 1014 m/s
D) 1710 m/s
C) E  
D) E  1/
2. What is the correct relationship?
A)   1/
B)   
3. Which type of electromagnetic radiation is the least energetic?
A) gamma rays
B) microwaves
C) ultraviolet
D) Radio waves
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4. When will a dark spot appear during light diffraction?
A) constructive interference
C) deconstructive interference
B) across from a slit
D) Not enough information
5. What is the energy of 1200 nm light?
A) 2.5 x 1014 J
B) 1.7 x 10-19 J
C) 1.7 x 10-27 J
D) 3.0 x 10-19 J
6. Light will be emitted from an atom when an electron is
A) Excited from the ground state B) In the ground state
C) Relaxed to the ground state D) Light is never emitted from atoms
7. What is the wavelength of light needed to excite an electron from n=2 to n=3?
A) -6.60 x 10-7 m
B) 656 nm
C) 457 nm
D) 700 nm
8. A low flow of electrons passed through 2 slits will not produce a diffraction pattern.
A) True
B) False
9. How many electrons can have the value n=3?
A) 18
B) 10
C) 6
D) 2
10. The angular momentum quantum number describes:
A) the spin direction of the electron
C) the shape of the orbital
B) the overall size and energy of the orbital
D) the orientation of the orbital
11. Which set of quantum numbers is valid?
A) n=0 l =1 ml=1 ms=+1/2
C) n=1 l =1 ml=0 ms=+1/2
B) n=1 l =0 ml=0 ms=0
D) n=1 l =0 ml=0 ms=+1/2
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Use the following diagram to answer questions 12-15
12. What is the value of l?
A) l =0
B) l =1
C) l =2
D) l =3
C) n=3
D) Not enough info
C) 2
D) Not enough info
13. What is the value of n?
A) n=1
B) n=2
14. How many electrons can reside in the orbital?
A) 0
B) 1
15. The law that dictates your answer to question 14 is named for whom?
A) Schrodinger
B) Pauli
C) Heisenberg
D) Bohr
16. The orbitals with equal n in a hydrogen atom are degenerate.
A) True
B) False
17. What is the covalent radius of Cl if the bond length of Cl2 is 198 pm?
A) 198 pm
B) 99 pm
C) 5.66 pm
D) 398 pm
18. What is the ground state electron configuration of Ca?
A) 1s22s22p63s23p64s2
C) 1s22s22p63s2
B) 1s22s22p63s23p8
D) 1s12s22p63s23p64s2
19. What is the effective nuclear charge felt by the electrons in the 4s orbital of Ca?
A) +1
B) +2
C) +18
D) +20
20. What is the electron configuration of the fluoride ion?
A) 1s22s22p5
B) 1s22s22p4
C) 1s22s22p6
D) Not enough info
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21. Which orbital diagram shows a diamagnetic element? Answer is Choice A
22. Which series correctly describes the trend in atomic radius?
A) Li < Na < K < Rb
C) Li = Na = K = Rb
B) Li > Na > K > Rb
D) Na < K < Rb < Li
23. Which best describes the size relationship between aluminum’s ionic radius and atomic
radius?
A) atomic < ionic
B) atomic > ionic
C) atomic = ionic
D) Not enough info
24. Why did you select the answer you did in question 23?
A) More electrons would cause the radius to expand
B) More electrons would cause the radius to contract
C) Less electrons would cause the radius to expand
D) Less electrons would cause the radius to contract
25. Which element has the highest first ionization energy?
A) Ne
B) Na
C) Xe
D) K
26. Energy is released when a ground state noble gas gains an electron
A) True
B) False
C) Not enough information
27. Consider this set of successive ionization energies, which 3rd row element do they belong
to?
IE1 = 496 kJ/mol
IE2 = 4560 kJ/mol
IE3 = 6910 kJ/mole
A) Si
B) Al
C) Mg
D) Na
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Useful information and equations
Avogadro’s Number = 6.022 x 1023 mol-1
h = 6.626 x 10-34 J s
0 C = 273 K
mass e- = 9.109 x 10-31 kg
c = 3.00 x 108 m/s
1 J = 1 kg m2/s2
En = (-2.181 x 10-18 J)(1/n2)
1
𝜆
= 𝑅[
1
1
𝑚
𝑛2
2 −
]
R=1.097 x 107 m-1
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