Electronic Structure and Periodicity

19. (Electromagnetic radiation, spectroscopy) Which wave has a higher frequency?

A, B, both have the same frequency

21. (Electronic configuration) Mn: [Ar]4s2 3d? How many d electrons does Mn have?

4, 5, 6

22. (Electronic configuration, valence electrons) Which electrons are most likely to be involved in chemical reactions?

those nearest to the nucleus, those farthest from the nucleus, all are equally likely to be involved

23. (Ionic radius) Which is larger,

Na+ or Na?
Cl or Cl-?

24. (Valence electrons) How many valence electrons are in Cl, [Ne]3s2 3p5?

2, 5, 7

For Cl to achieve a noble gas configuration, it is more likely that

electrons would be added, electrons would be removed

25. (Lewis dot structures, octet rule) What is a correct Lewis dot representation of carbon monoxide?

26. (Lewis dot structures, bonding) Compare O-O and O=O. Is O=O expected to be

stronger, weaker, or the same strength?

Is O=O expected to be

longer, shorter, or the same length?

37. (Isoelectronic structures, periodic properties; Ch. 7 "Companion") Ge is a semiconductor. If half of the Ge atoms of a sample of Ge are replaced with Ga atoms, with what element should the other half of the Ga atoms be replaced in order for this new compound to be isoelectronic with Ge?

Sn, As, Se

38. (Band gap energy, spectroscopy, semiconductors; Ch. 7 "Companion") Setup: Band gap energy has been introduced in a localized picture: it can be defined as the energy needed to remove an electron from a bond in the solid, enabling the electron to move freely through the solid to conduct electricity. When itinerant electrons return to such a one-electron bond, the band gap energy can be released as a photon. The band gap energy is to a first approximation expected to increase as the bonds become stronger and shorter and the electrons are held more tightly. The group 14 elements illustrate this effect with diamond being an electrical insulator, silicon and germanium (longer, weaker bonds in the same diamond structure) being semiconductors, and tin being a metal. Demonstration 7.11 "Companion": A trio of related predictions: what will happen to interatomic spacing, band gap energy, and the color of the light emitted when an orange LED is cooled in liquid nitrogen. On cooling,

atoms of the semiconductor will get closer together, atoms will get farther apart
band gap energy increases, band gap energy decreases
color of light will become more red, color of light will become more yellow

40. (Spectroscopy; Ch. 7 "Companion") Knowing diamond is transparent, which curve best represents the absorption spectrum of diamond (see below)?

A, B, C

41. (Superconductors, periodic properties; Ch. 9 "Companion") A major research breakthrough was the discovery that an oxide of La, Cu, and Ba was superconducting. When this material was "squeezed," the high pressure raised the critical temperature at which it became superconducting. Given this effect, which element should be tried as a +3 ion replacement for La to raise the critical temperature without having to apply pressure?

Hf, Y, Ac

51. (Solid solutions, periodic properties; Ch. 7 "Companion") Which of the following is a reasonable solid solution?

GaxAl1-xAs, GaPxAs1-x, GaAlxAs1-x

55. (Energy diagrams) According to the energy diagram below for the Bohr model of the hydrogen atom, if an electron jumps from E1 to E2, energy is

absorbed, emitted, not involved

56. (Magnetism, unpaired electrons; Ch. 2 "Companion") Two gel capsules, A and B, are filled with KMnO4 and MnO2, respectively. Based on Mn formal oxidation state and numbers of unpaired electrons, which will have a stronger attraction to a magnet?

A, B

Demonstration 2.2 "Companion": Fill one gel capsule with KMnO4 (Mn+7, do), another with MnO2 (Mn+4, d3) and a third with Fe (or Co, Ni) powder. Bring a strong magnet near and even touching the KMnO4 capsule. Note the lack of any attraction. Repeat with the MnO2 capsule, which will be weakly attracted to the magnet due to the unpaired electrons. The Fe capsule will jump to the magnet illustrating the much stronger magnetic attraction for the ferromagnetic material with its cooperative electronic interactions. For large audiences, this demonstration can be done on an overhead projector.

57. (Transition metal complexes) Ti(H2O)63+ has how many d-electrons?

d0, d1, d2

With regard to magnetic properties, Ti(H2O)63+ is

paramagnetic, diamagnetic?

Ti(H2O)63+ absorbs yellow light. Based on complementary color relationships (color wheel), what color does it appear?

red, green, violet

58. (d-orbitals) Co2+ has seven electrons in its d-orbitals, which are split as shown below in octahedral coordination geometry. In a high spin configuration, how many electrons are unpaired?

1, 2, 3

In a low spin configuration, how many electrons are unpaired?

1, 2, 3

67. (Spectroscopy, probability; Ch. 8 "Companion") If a blue cupric solution cuts the amount of red laser light reaching a solar cell, which counts photons as photocurrent, in half...

...what will happen if a second solution is added?

79. (Magnetism, polarity, surfactants; Ch. 2 "Companion," Demonstrations 2.6, 2.7) In a ferrofluid preparation, the intent is to keep magnetic particles suspended in an oily medium. How do the surfactant molecules interact with this medium?

A, B

83. (Doping, semiconductors, periodic properties; Ch. 8 "Companion") Which dopant will act as an acceptor for Si?

B, Ge, As

As a donor?

B, Ge, As

95. (Spectroscopy) Demonstration: The current measured in the set-up below is 2 mA. If the sealed sample cell containing a light-absorbing solution is turned lengthwise, what current will be measured?

>2 mA, =2 mA, <2 mA

96. (Transition metal complexes) For octahedral complexes, which metal ion fills the 3d subshell with electrons?

Ni2+, Cu2+, Zn2+

What color is predicted based on the possible d-d transitions of this complex?

white, red, black

103. (Band gap energy; Ch. 7 & 8 "Companion") For promoting electrons to the conduction band and forming e--h+ pairs, which photons are the most energy efficent?

hv>Eg, hv=Eg, hv<Eg

109. (Semiconductors; Ch. 7 "Companion") A CdS photocell measures light intensity by its change in resistance. If the intensity of light increases, the CdS resistance

increases, decreases, stays constant

115. (Electronegativity, bonding, band gap energy; Ch. 7 "Companion") The atoms below have the following electronegativities:

The three isoelectronic semiconductors Ge, GaAs, and ZnSe all have roughly the same size unit cell and internuclear separation (exclusively Ge-Ge, Ga-As, and Zn-Se bonds, respectively). If under these conditions, band gap energy increases with ionic character, which isoelectronic solid should have the largest band gap energy?

Ge, GaAs, ZnSe

119. (Coordination chemistry) Consider the complex CrF63- with anionic F- ligands. What is the formal oxidation state of the chromium?

3, 0, -3

120. (Coordination chemistry) Which of the following are isoelectronic with the H2O molecule, which commonly serves as a ligand?

methane CH4, ammonia NH3, fluoride F-

Which of the above could serve as a ligand if lone pairs are required for binding to the metal center?

methane CH4, ammonia NH3, fluoride F-

More questions are needed for this section. Please submit contributions to concept@chem.wisc.edu..