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Study Question for the Final Quiz on Quantum Theory of Atoms and Molecules

USEFUL INFORMATION Conversion Factors

Mass Length 1 kg = 1000 g 1 g = 1000 mg Mass electron: me = 9.11 × 10-31 kg

1 mm = 10-3 m 1 cm = 10-2 m 1 km = 1000 m 1 nm = 10-9 m 1 Å = 10-10 m

Energy Constants 1 kJ = 1000 J 1 eV = 1.60218 × 10-19 J

Planck’s Constant: h = 6.626 × 10-34 Js Avogadro’s Number: 6.022 ×1023 particles/mol speed of light in vacuum: c = 3.00 × 108 m/s J = kg m2/s2

Frequency Bond Polarity Hz = s-1 MHz = 106 Hz THz = 1012 Hz

0 ≤ ∆𝜒 ≤ 0.4𝑖𝑠𝑛𝑜𝑛𝑝𝑜𝑙𝑎𝑟𝑐𝑜𝑣𝑎𝑙𝑒𝑛𝑡 0.4 ≤ ∆𝜒 ≤ 2.0𝑖𝑠𝑝𝑜𝑙𝑎𝑟𝑐𝑜𝑣𝑎𝑙𝑒𝑛𝑡

2.0 ≤ ∆𝜒𝑖𝑠𝑖𝑜𝑛𝑖𝑐 Useful Equations Wave equation

𝑐 = 𝜆 ∙ 𝜈 Planck’s Equation

𝐸 = ℎ ∙ 𝜈 =ℎ ∙ 𝑐𝜆

Photoelectric effect

𝐾𝐸 =12𝑚?𝑣?@ = ℎ ∙ (𝜐 − 𝜐DEF?GEHIJ) = ℎ𝜐 − 𝑏𝑖𝑛𝑑𝑖𝑛𝑔𝑒𝑛𝑒𝑟𝑔𝑦

Energy levels in the Hydrogen atom

𝐸P = −13.6𝑒𝑉 × T1𝑛@U

De Broglie’s Equation

𝜆 =ℎ

𝑚 ∙ 𝑣 =ℎ𝑝

(here 𝑝 = 𝑚 ∙ 𝑣 is called the momentum of the particle)

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Start Here 1.Theemissionspectrumofgoldshowsalineofwavelength2.676x10-7m.Howmuchenergyisemittedastheexcitedelectronfallstothelowerenergylevel?

a.7.43x10-19Jb.5.30x10-20Jc.6.05x10-19Jd.3.60x10-20Je.5.16x10-20J

2.Whatisthefrequencyoflighthavingawavelengthof4.50x10-6cm?

a.2.84x10-12s-1b.2.10x104s-1c.4.29x1014s-1d.1.06x1022s-1e.6.67x1015s-1

3. Bohr’s atomic model

a. Proposes that electrons occupy specific energy levels b. Explains the emission spectra of H atoms c. Predicts the energy levels of multi-electron atoms d. Both a and b are true e. Answers a, b and c are all true

Questions 4-6: In the Bohr model the energy level n (where n = 1, 2, 3, 4 …) is given by the equation

𝐸P = −13.60𝑒𝑉 × T1𝑛@U

4. How much energy is released when an electron in n = 4 drops to the n = 3 state? a. 2.043 x 10-18 J b. 3.981 x 10-18 J c. 1.938 x 10-18 J d. 1.060 x 10-19 J e. None of the above

5. What is the frequency of the light emitted/absorbed in the previous question?

a. 1.60 x 1014 Hz b. 6.31 x 10-15 Hz c. 1.89 x 10-4 Hz d. 9.96 x 10-53 Hz e. None of these are correct

6. What type of light would be emitted/absorbed in the previous question?

a. Ultra-Violet b. Visible c. Infrared d. Microwave e. X-rays

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7. The quantum mechanical model of the atoms

a. Describes the electrons using a probability distribution that determines the most likely location of the electrons

b. Is the currently accepted model of the atom c. Makes its predictions by solving the Schrödinger equation d. Answers a and c are correct e. Answers a, b and c are correct

8. In the quantum mechanical model of the atom, which of the following is NOT one of the four quantum numbers needed to specify the probable location of an electron?

a. Principle quantum number (n) which describes the energy level/distance from the nucleus b. The Heisenberg number (h) which describes the electron’s position and speed c. Angular momentum quantum number (l) which describes the shape of the orbital d. The magnetic quantum number (ml) which describes the orbital’s orientation in space e. All of the above are legitimate quantum numbers

9. The Heisenberg Principle states that _____________.

a. no two electrons in the same atom can have the same set of four quantum numbers. b. two atoms of the same element must have the same number of protons. c. it is impossible to determine accurately both the position and velocity of an electron simultaneously. d. electrons of atoms in their ground states enter energetically equivalent sets of orbitals singly before they pair up in any orbital of the set. e. charged atoms (ions) must generate a magnetic field when they are in motion.

10. Which statement about the four quantum numbers which describe electrons in atoms is incorrect?

a. n = principal quantum number, n = 1, 2, 3, ...... b. l = subsidiary (or azimuthal) quantum number, l = 1, 2, 3, ... , (n+1) c. ml = magnetic quantum number, ml = (-l), .... , 0, .... , (+l) d. ms = spin quantum number, ms = +1/2 or -1/2. e. The magnetic quantum number is related to the orientation of atomic orbitals in space.

11.Whichatomicorbitalissphericalinshape?(Note:youshouldknowandbeabletorecognizetheshapesofthesorbital,px,py,andpzorbitals,anddxy,dyz,dxz,dx2-y2anddz2orbitals.)

a.2sb.3pc.3dd.4fe.theyareallspherical

12.Themaximumnumberofelectronsthatcanbeaccommodatedinasublevelforwhichl=3is:

a.2b.10c.6d.14e.8

13. The word Aufbau is German and means ‘building up’. The Aufbau principle describes that

a. Electrons with the same spin cannot occupy the same orbital b. Since electrons repel each other, electrons first occupy orbitals singly before doubling up c. Electrons fill the lower energy orbitals first before occupying the higher energy orbitals d. None of the above

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14. Which of the following configurations violates the Aufbau principle?

a.

b.

c.

d.

15. Which of the following configurations violates the Pauli Exclusion Principle?

a.

b.

c.

d.

16. Which of the following configurations is the correct one for the Nitrogen atom?

a.

b.

c.

d.

17.Thegroundstateelectronconfigurationforarsenicis:

a.[Ar]4s24p13b.[Kr]4s24p1c.1s22s22p63s23p63d124s24p1d.1s22s22p63s23p64s23d84p5e.1s22s22p63s23p64s23d104p3

18.Whichofthefollowingelectronconfigurationsiscorrectfornickel?

a.[Ar]4s13d8b.[Kr]4s14d8c.[Kr]4s13d8d.[Kr]4s23d8e.[Ar]4s23d8

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19.Theouterelectronicconfigurationns2np4correspondstowhichoneofthefollowingelementsinitsgroundstate?

a.Asb.Cac.Crd.Bre.S

20.Inthegroundstateofacobaltatomthereare_____unpairedelectronsandtheatomis_____.

a.3,paramagneticb.5,paramagneticc.2,diamagneticd.0,diamagnetice.2,paramagnetic

21. After the 5s subshell of an atom is filled with electrons, the next electron added will enter the

a. 4d subshell. b. 5p subshell. c. 5d subshell. d. 6s subshell.

22. How many unpaired electrons are present in the orbital diagram for an atom whose electron configuration is 1s22s22p4?

a. 0 b. 1 c. 2 d. 4

23. The elements in group IVA of the periodic table all have electron configurations ending in

a. p2. b. p4. c. d4. d. s2.

24. The threshold frequency for photoelectric emission in Copper is 1.1x 1015 Hz. Find the maximum kinetic energy of the photoelectrons emitted when light of frequency 1.5 x 1015 Hz is directed on a Copper surface.

a. 1.65 eV b. 1.32 eV c. 2.40 eV d. 3.22 eV

25. The threshold wavelength for photoelectric emission in Tungsten is 240. nm. What wavelength of light must be used in order that the emitted photoelectrons have a Kinetic Energy (KE) of 1.2 eV (see conversion table)

a. 200 nm b. 230 nm c. 350 nm d. 195 nm

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26. The photoelectric effect only occurs if the light shining on the metal is a. Coherent (from a laser) b. Above a minimum intensity (how bright the light source is) c. Above a minimum frequency d. Above a minimum wavelength

27. Color depends on what characteristic of light

a. its frequency b. its wavelength c. its intensity d. all of these e. just a and b

28. All of the waves listed below are a part of the electromagnetic spectrum except a. sound waves. b. X rays. c. gamma rays. d. light waves. e. radio waves. 29. Diffraction (see right) is a result of a. refraction. b. reflection. c. interference. d. polarization. e. dispersion. 30. Compared to ultraviolet waves, the wavelength of infrared waves is a. shorter. b. longer. c. faster. d. slower. e. the same 31. Interference is a property of

a. light waves. b. sound waves. c. water waves. d. all of these. e. none of these.

32. Electromagnetic waves consist of

a. compressions and rarefactions. b. oscillating electric and magnetic fields. c. particles of light energy. d. high-frequency gravitational waves.

33. Refraction results from differences in light's a. frequency. b. amplitude. c. speed. d. all of these. e. none of these.

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34. The effect in which white light separates into different colors is called

a. magnification b. refraction c. reflection d. dispersion

35. Which part of the Electromagnetic Spectrum can cause polar molecules to rotate?

a. Ultra-Violet b. Visible c. Infra-Red d. Microwaves e. Radio Waves

36. Which part of the Electromagnetic Spectrum can cause polar molecules to vibrate?

a. Gamma Rays b. X-Rays c. Visible d. Infra-Red e. Radio Waves

37. Which part of the Electromagnetic Spectrum has the longest wavelengths?

a. Gamma Rays b. X-Rays c. Visible d. Infra-Red e. Radio Waves

38. Which part of the Electromagnetic Spectrum has the largest (highest) frequencies?

a. Gamma Rays b. X-Rays c. Visible d. Infra-Red e. Radio Waves

39. When two waves interact to create a larger wave, what type of interference is occurring?

a. Constructive Interference b. Destructive Interference

40. When two waves interact to cancel one another out, what type of interference is occurring?

a. Constructive Interference b. Destructive Interference

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41. The binding energy of electrons in a metal is 200 kJ/mol. Find the threshold frequency of the metal

42. A laser shines violet light with a frequency of 700. THz onto the metal in the previous question, what is the kinetic energy of the ejected electrons?

43. How fast are the electrons traveling in m/s? (Assume the electron has a mass of 9.109x10-31 kg)

44. Which of the following does not appear in the de Broglie equation for a particle?

a. Wavelength b. Velocity c. Planck’s constant d. Particle’s position

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45. What is the main point of the de Broglie equation?

a. The position of light cannot be precisely determined b. Matter has wave-like properties c. Matter only behaves like a particle d. Einstein’s theory of relativity was incorrect

46. The de Broglie wavelength of an electron with a kinetic energy of 500. eV is

a. 54.8 Å b. 0.548 Å c. 5480 Å d. 5.48 Å

47. A wave associated with a moving particle is called

a. Longitudinal wave b. Mechanical wave c. De Broglie wave d. Planck’s wave

48. The momentum of an electron, p, (where p = 𝑚? × 𝑣?), if its wavelength is 2.0 Å, is

a. 2.3 x 10-24 kg m/s b. 3.3 x 10-24 kg m/s c. 1.3 x 10-24 kg m/s d. 13 x 10-24 kg m/s

Lewis Structures and VSEPR 49. Which is the correct Lewis dot structure for HCN?

a. b.

c.

d.

50. Which is the true limitation of Lewis Structure

a. Doesn’t tell you which atoms is bonded to one another b. Doesn’t tell you the shape of the molecule c. Doesn’t tell you the number of bonds d. None of the above

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51. Which is the correct structure for HNO3?

a.

b.

c.

d.

52. Which is the correct structure for H2CO3?

a.

b.

c.

d.

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For each of the compound characterizations on the left, select from the response list on the right the appropriate Lewis structure. Responses on the right may be used more than once or need not be used at all. 53. Compound with a trigonal pyramidal geometry 54. Compound that is nonpolar 55. Compound that has a bent geometry 56. Compound that contains both polar and nonpolar bonds 57. Compound in which the arrangement of electron groups about

the central atom is not tetrahedral

58. What is the correct molecular geometry for IF5?

a. Tetrahedral b. Trigonal bipyramidal c. Octahedral d. Square pyramidal e. Seesaw

59. Which of the following molecules is non-polar?

a. H2O b. NH3 c. CO d. CO2 e. All are polar

60. What should the Lewis structure for N2 look like?

a. 1 quadruple bond between the two N atoms b. 1 N=N double bond and two lone pairs on each N atom c. 1 N-N single bond and three lone pairs on each N atom d. 1 N≡N triple bond and one lone pair on each N atom

H O Ha)

NN Ob)

H P H

H

c)

H C H

H

H

d)

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In Valence Bond Theory it is often necessary to hybridize the valence orbitals. In the table below assign the hybridization of the atom of interest,

Question # molecule Atom of

interest Type of hybridization

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Carbon

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

62

Carbon

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

63

Carbon

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

64

Phosphorus

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

65

Sulfur

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

66

Xenon

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

67

Carbon

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

68

Carbon

a. sp b. sp2 c. sp3 d. sp3d e. sp3d2

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69. Show the ground state electron configuration for N2 (note this is just showing the valence electrons)

70. Calculate the bond-order for this molecule

71. Is the molecule

a. Paramagnetic b. Diamagnetic

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72. Using the above diagram show the electron configuration for O2 (again note this is just the valence electrons) 73. Calculate the bond-order for this molecule

74. Is the molecule

a. Paramagnetic b. Diamagnetic

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Redemption Saloon 75. Get BOTH parts essentially correct and this is added to your grade in Quiz 3 When butane (C4H10) is burnt in air the products are carbon dioxide and water

C4H10(g) + WX@

O2(g) ¾® 4CO2(g) + 5H2O(l) Given the following thermodynamic data,

A. Calculate the enthalpy for the reaction at STP

B. Assuming that all the heat from combustion of butane, how many grams of propane

(Molar Mass 44.1 g/mol) are needed to heat 400 L of water from 25.0oC to 35.0oC (Assume the density of water is 1.0 g/ml and that the heat capacity of water is 4.184 J/(g oC)

substance 𝜟𝑯𝒇

𝒐 (kJ/mol)

C3H10(g) -125.6

O2(g) 0.000

CO2(g) -393.5

H2O(l) -285.8

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