CHAPTER 4

ATOMS AND LIGHT

CHAPTER STUDY OBJECTIVES

1. Understand some of the fundamental aspects of atoms.

SKILLS TO MASTER: Calculating the volume of a single atom

KEY CONCEPTS: Atoms have mass, contain positive nuclei, contain electrons, and occupy volume.

2. Understand some of the fundamental aspects of light.

SKILLS TO MASTER: Interconverting frequency and wavelength of light; calculating photon energies from frequency or wavelength; calculating the energies of electrons ejected by the photoelectric effect

KEY CONCEPTS: Light has wave-like and particle-like characteristics.

3. Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

SKILLS TO MASTER: Calculating energies of electrons in hydrogen atoms; working with energy-level diagrams

KEY CONCEPTS: The energies of electrons in atoms are quantized.

4. Describe properties of free electrons and those in atoms or molecules.

SKILLS TO MASTER: Using the de Broglie equation; using the uncertainty principle

KEY CONCEPTS: Electrons have particle-like and wave-like properties.

5. Write valid sets of quantum numbers for a given set of orbitals.

SKILLS TO MASTER: Determining sets of quantum numbers

KEY CONCEPTS: Each atomic electron energy level is associated with a specific three-dimensional atomic orbital. The principal quantum number (n) must be a positive integer. The azimuthal quantum number (l) can be zero or any positive integer smaller than n. The magnetic quantum number (ml) ranges from –l to +l. The spin quantum number (ms) can be +1/2 or −1/2.

6. Recognize shapes of s, p, d, and f orbitals.

7. Describe the major chemical reactions in the troposphere and stratosphere and explain the chemistry of the greenhouse effect.

Multiple Choice QUESTIONS

1. One of the characteristics of atoms is that they attract one another. What characteristic of gases supports this notion?

a) Equal numbers of molecules occupy equal volumes.

b) Gas molecules have a small, but definite volume.

c) The volume of a gas increases with increasing temperature.

d) Non-ideal behaviour is observed at low temperatures.

e) Volume decreases with increasing pressure.

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

2. The volume of an atom is determined by

a) the number of protons in the nucleus.

b) the number of protons and neutrons in the nucleus.

c) the number of electrons in the nucleus.

d) the electron cloud surrounding the nucleus.

e) the period it occupies in the periodic table.

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

Feedback: In choosing correct answer d, the student recognizes that volume is determined by the size of the electron cloud, and also that atoms contain empty space. Distracter e) is added to emphasize that the periodic table is comprised of atomic properties and does not determine the properties itself.

3. The mass of an atom is determined by

a) the number of protons in the nucleus.

b) the number of protons and neutrons in the nucleus.

c) the number of electrons in the electron cloud surrounding the nucleus.

d) the number of neutrons and electrons.

e) the period it occupies in the periodic table.

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

Feedback: In choosing correct answer b, the student recognizes that volume is determined by the size of the electron cloud, and also that atoms contain empty space. Distracter e) is added to emphasize that periodic table is comprised of atomic properties and does not determine the properties itself.

4. Most of the volume of an atom is made up of

a) electrons.

b) protons.

c) neutrons.

d) protons and neutrons.

e) empty space.

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

Feedback: Student must recognize that while protons and neutrons make up the mass of the atom, and the electron cloud determines the size, much of the atom is empty space.

5. When a gas such as argon condenses

a) atoms combine with one another to form chemical bonds.

b) atoms are attracted to one another due to electrical forces acting between electrons on one atom and protons of the other.

c) electrons of one atom repel those on another causing the gas to condense and form a liquid.

d) atoms are attracted to one another due to electrical forces acting between electrons on one atom and neutrons of the other.

e) atoms are attracted to one another due to electrical forces acting between neutrons on each of the atoms.

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

Use the following equations for Questions 6–10.

c = 3.0 x10⁸m/s = E = h h = 6.626 x 10^-34 J•s

E = h – h₀; E = ½ mv² (KE of an electron) mass_e = 9.11 x 10^-31 kg

6. Which of the following provides the greatest energy?

a) 5.00 x 10¹⁰ photons of frequency 1.00 x10⁹ 1/s

b) 7.00 x 10⁶ photons of wavelength 550 nm

c) 5.00 x 10⁵ photons of frequency 1.05 x 10¹⁴ 1/s

d) 7.20 x10⁸ photons of wavelength 200 nm

e) 5.00 x 10¹⁵ photons of wavelength 15 m

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

7. Which of the following radiation is the most energetic?

a) radiation of wavelength 500 nm

b) radiation of frequency 5.76 x10¹⁴ Hz

c) radiation of frequency 8.25 x10¹⁴ Hz

d) radiation of wavelength 250 nm

e) cannot be determined based on the information given

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

8. Sodium emits yellow light of wavelength 690nm when heated in a flame. What is the frequency of this light?

a) 2.07 x 10¹¹ s^-1

b) 4.35 x 10⁵ s^-1

c) 4.35 x10¹⁴ s^-1

d) 207 nm

e) 1.04 x 10¹⁴ s^-1

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

9. Chromium metal has a binding energy of 7.21 x 10^-19J for certain electrons. What is the photon frequency needed to eject electrons with 2.2 x 10^-19J of energy?

a) 1.4 x 10¹⁵ s^-1

b) 2.4 x 10¹⁵ s^-1

c) 5.5 x 10¹⁵ s^-1

d) 1.2 x 10¹⁴ s^-1

e) 1.3 x 10¹⁶ s^-1

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

10. Chromium metal, binding energy of 7.21 x 10^-19J for certain electrons, is subjected to a photon source of frequency 1.4 x 10¹⁵ s^-1. If the intensity of the photon source in increased, one would expect

a) the energy of the ejected electrons to increase.

b) the energy of the ejected electrons to decrease.

c) the number of ejected electrons to increase.

d) the number of ejected electrons to decrease.

e) no change.

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

Feedback: understanding of the meaning of intensity

Use the following equations for Questions 11–15.

; E_n =

11. If a hydrogen atom is excited into the n = 4 state, how many transitions are possible by emitting electromagnetic radiation?

a) 1

b) 2

c) 3

d) 4

e) 5

Difficulty: Easy

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

12. An electron in an H atom is excited to an energy level of –8.72 x 10^-20 J. What energy level does this correspond with?

a) 2

b) 3

c) 4

d) 5

e) 6

Difficulty: Easy

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

13. An excited electron on a hydrogen atom releases a photon as it falls from energy level 6 to level 3. What is the wavelength of the photon released?

a) 2.74 x10¹⁶ s^-1

b) 2.18 x10^-16 J

c) 1090 nm

d) 109 nm

e) 3 m

Difficulty: Easy

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

14. An excited electron on a hydrogen atom releases a photon as it falls from energy level 6 to level 3. What is the change in energy of the atom and the energy of the photon released?

a) 1.1 x10⁵ J, 1.1x10⁵ J

b) –1.1x10⁵ J, 1.1x10⁵ J

c) 1.8x10^-19 J, 1.8x10^-19 J

d) –1.8x10^-19 J, –1.8x10^-19 J

e) –1.8x10^-19 J, 1.8x10^-19 J

Difficulty: Medium

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

Feedback: a) out by a factor of Avogadro’s number, also, fails to recognize that emission results in a lower of the atoms energy; b) out by a factor of Avogadro’s number; c) fails to recognize that atom loses energy on emission of a photon; d) photon energy is positive; e) correct answer

15. A hydrogen atom absorbs a photon resulting in an electron transitioning from the n = 2 to n = 5 energy level. What is the wavelength of the absorbed photon and what is the change in energy of the atom?

a) 434 μm, 4.6x10^-19 J

b) 434 μm, –4.6x10^-19 J

c) 434 nm, –4.6x10^-19 J

d) 434 nm, 4.6x10^-19 J

e) 6.9x10¹⁴ s^-1, 4.6x10^-19 J

Difficulty: Medium

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

Feedback: a) units are incorrect; b) units are incorrect, change in energy should be positive; c) change in energy is positive on adsorption of photon; d) correct answer; e) photon is described by frequency not by wavelength

Use the following equations for Questions 16–18.

E_kinetic = ½ mv²; mass_e = 9.11 x 10^-31kg;

16. What is the wavelength of a proton (m = 1.67 x 10^-27 kg) moving at 1.2 x 10⁵ m/s?

a) 0.033 nm

b) 3.3 x 10^-2 nm

c) 3.3 x 10^-9 m

d) 3.3 x 10^-12 m

e) 3.3 nm

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

17. The Heisenberg uncertainty principle

a) places limits on the accuracy of measuring both position and motion.

b) is most important for microscopic objects.

c) makes the idea of “orbits” for electrons meaningless.

d) a, b

e) a, b and c

Difficulty: Medium

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

Feedback: This question evaluates if students distinguish between an orbit and an orbital.

18. Which of the following objects would we expect NOT to have any meaningful wave properties?

a) electrons

b) protons

c) neutrons

d) a mole of carbon atoms

e) photons

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

Use the following equations for Questions 19–29.

E_n =

19. Which of the following set of quantum numbers is NOT possible?

a) n =2, l = 1, m_l = 0, m_s =1/2

b) n =3, l = 2, m_l = 2, m_s =1/2

c) n =4, l = 2, m_l = 2, m_s = –1/2

d) n =3, l = 3, m_l = 2, m_s = –1/2

e) n = 2, l = 1, m_l = 1, m_s = –1/2

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

20. Which of the following set of quantum numbers is possible?

a) n =2, l = 0, m_l = 1, m_s =1/2

b) n =3, l = 3, m_l = 2, m_s =1/2

c) n =4, l = 3, m_l = 3, m_s = –1/2

d) n =3, l = 3, m_l = 2, m_s = –1/2

e) n = 2, l = 1, m_l = 2, m_s = –1/2

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

21. Which of the following sets of quantum numbers is valid for an electron in a 4d orbital?

a) n =4, l=1, m_l=1, m_s =1/2

b) n =4, l=2, m_l=3, m_s = –1/2

c) n =4, l=3, m_l=2, m_s =1/2

d) n =4, l=2, m_l=1, m_s = –1/2

e) n =4, l=0, m_l=0, m_s = –1/2

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

22. Which of the following sets of quantum numbers is valid for an electron in a 4f orbital?

a) n =4, l=1, m_l=1, m_s =1/2

b) n =4, l=3, m_l=4, m_s = –1/2

c) n =4, l=3, m_l=2, m_s =1/2

d) n =4, l=2, m_l=1, m_s = –1/2

e) n =4, l=4, m_l=1, m_s = 1/2

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

23. An electron in an H atom is excited to an energy of –8.72 x 10^-20 J which corresponds to a primary level 5. What is the largest value of m_l possible for this energy level?

a) 3

b) 4

c) 5

d) 6

e) 9

Difficulty: Medium

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

24. An electron in an H atom is excited to an energy of –8.72 x 10^-20 J which corresponds to a primary level 5. How many possible m_l values are there for this energy level?

a) 4

b) 18

c) 5

d) 11

e) 9

Difficulty: Medium

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

Feedback: a) l = 4, this does not mean 4 degenerate energy levels; b) there are 18 possible ways to describe this electron as each of the 9 degenerate energy levels can accommodate either spin up or spin down electron; c) the number of energy levels is not equivalent to n; d) based on l = 5; e) correct answer

25. An electron in an H atom is excited to an energy of –2.42 x 10^-19 J. What is the largest value of m_l possible for this energy level?

a) 1

b) 2

c) 3

d) 0

e) 7

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

26. The magnetic quantum number

a) is always less than the value of l.

b) is always less than n.

c) is always greater than m_s.

d) correlates strongly with the energy of the electron.

e) must be a positive number.

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

27. The principle quantum number for the outermost 2 electrons in Sr would be

a) 3.

b) 4.

c) 5.

d) 6.

e) 2.

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

28. The principle quantum number for the 3 outermost electrons in Sc are

a) 3, 3 and 3.

b) 4, 4 and 3.

c) 4, 4 and 4.

d) 3, 3, and 4.

e) 4, 4, and 5.

Difficulty: Medium

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

Feedback: The student needs to be able to read the periodic table and recognize that atoms with 3d electrons are in the 4^th row.

29. The azimuthal quantum number for the outermost electron on K is

a) 0.

b) 1.

c) 2.

d) 3.

e) 4.

Difficulty: Medium

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

30. How many nodes are there in a 3p orbital?

a) 0

b) 1

c) 2

d) 3

e) 4

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

31. An electron in which subshell will, on average, be closer to the nucleus of an atom?

a) 3s

b) 3p

c) 3d

d) 4d

e) 4s

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

32. Which atom has a smaller 3s orbital?

a) an atom with more protons

b) an atom with fewer protons

c) an atom with more neutrons

d) an atom with fewer neutrons

e) the size of the 3s orbital is the same for all atoms.

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

33. How many orbitals are there in the d sublevel?

a) 1

b) 3

c) 5

d) 6

e) 7

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

34. The quantum numbers that correspond to size and orientation of orbitals are

a) principal and azimuthal.

b) principal and magnetic.

c) azimuthal and magnetic.

d) n and l.

e) azimuthal and spin.

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

35. What wavelength photons are required to “split” molecular O₂ into O atoms?

a) microwave region of wavelengths

b) infrared region of wavelengths

c) 280–320 nm

d) 240–280 nm

e) 180–220 nm

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

36. What is the main reason for CO₂’s significant participation in global warming?

a) its high concentration

b) its rapid destruction in the atmosphere

c) its efficiency in absorbing visible light

d) its slow uptake into the biosphere

e) its efficiency in absorbing infrared light

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

37. Which of the following reactions is NOT predominant in the thermosphere?

a) N₂ +h 🡪N₂⁺

b) O₂ + h 🡪 2 O

c) CO + 1/2 O 🡪 CO₂

d) 2 O 🡪 O₂ + heat

e) N₂⁺🡪 N₂ + heat

Difficulty: Medium

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

38. The temperature at the last ice age was how much different than today’s average temperature?

a) It was the same on average.

b) 3˚ to 8˚ C warmer

c) 3˚ to 8˚ C colder

d) 10˚ to 20˚C colder

e) 20˚ to 30˚C colder

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

39. There are a number of layers in the atmosphere where oxygen molecules are broken into atoms that can combine with other O₂ molecules to make ozone (O₃). Why is it that there is only a specific region/layer where ozone is made in any significant amount?

a) The reaction is faster at higher altitudes.

b) The concentration of O₂ is not large enough at higher altitudes.

c) The energy from the sun is not strong enough at higher altitudes.

d) The molecules cannot breathe at higher altitudes.

e) The reaction is slow at higher altitudes.

Difficulty: Medium

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

ESSAY QUESTIONS

40. How would you explain to a friend the size of the nucleus of an atom versus the size of the entire atom?

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

41. How many electrons are present in 8.0 grams of He?

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

42. How many protons are in 3.5 moles of carbon atoms?

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

43. The density of lead is 11.34 g/cm³; if the lead nucleus is 1/100 000 times that of the atom, determine the density of the nucleus.

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

Feedback: Students must recognize that the mass of the atom is primarily determined by/confined to the nucleus.

44. The density of gold is 19.3 g cm^-3. Determine the radius of a single gold atom.

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of atoms.

Section Reference: 4.1 Characteristics of Atoms

Feedback: Assume atom is spherical.

45. Magnesium has a binding energy of 258.6 kJ/mole. If filtered light from a mercury lamp with wavelength 383 nm is absorbed by magnesium metal, what is the maximum kinetic energy of electrons observed?

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

46. Platinum is a quite inert metal used in many ways, recently popular in jewelry. It has a binding energy of 513 kJ/mole. What is the longest wavelength of electromagnetic radiation possible that will have enough energy to eject photoelectrons from a platinum atom?

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

47. Lasers are commonly used to mark and cut metals with high precision. One industrial laser is the neodymium-YAG laser that produces laser light of wavelength 1065 nm. If you want to vaporize 50 mg of Pt, which requires about 250 J of energy, how many photons of YAG laser light are needed?

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

48. The ruby laser contains chromium (III) ions in Al₂O₃. It is the Cr(III) ion that emits light of 627 nm under the laser emission conditions. If a ruby contains 0.0010% Cr by mass, what is the minimum mass of a ruby (in g) required to produce a single pulse with energy 1.5 J?

Difficulty: Medium

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

49. A glass filled with water absorbs 2.5 x 10²⁰ photons of wavelength 1500 nm. How much energy is transferred to the water?

Difficulty: Easy

Learning Objective: Understand some of the fundamental aspects of light.

Section Reference: 4.2 Characteristics of Light

50. An electron on a hydrogen atom in the outer atmosphere of a star can be excited to very high quantum numbers. What is the wavelength of light emitted when a hydrogen atom undergoes a transition from n = 1000 to n = 999?

Difficulty: Medium

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

51. Hydrogen atoms are present for fleeting amounts of time in combustion processes. They can be observed by monitoring the amount of light absorbed at the wavelength corresponding to the n = 2 to n = 3 transition. What is the wavelength of this electromagnetic radiation and in what region of the spectrum does it lie?

Difficulty: Medium

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

52. The energy levels of the dication of lithium, Li²⁺, are described by a modified Bohr equation; all energy levels are nine times those of the H atom. What is the wavelength (in nm) emitted by n Li²⁺ ion going from the n = 5 to n = 4 energy level?

Difficulty: Medium

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

53. A number of scientists, when they saw the hydrogen gas emission lines, thought that the electrons in the hydrogen atom could have any energy and that they were only seeing a few of those energies. How did Bohr interpret these emission lines and why was this a new or unique interpretation?

Difficulty: Easy

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

54. Show the path of an electron on an atom as it absorbs energy going from energy level 1 to level 6 and then releasing energy (as a photon) to fall to energy level 3. Be sure to show the relative differences in energy of the levels.

Difficulty: Easy

Learning Objective: Explain the origins of atomic spectra and relate electron energies in the hydrogen atom to its emission spectrum.

Section Reference: 4.3 Absorption and Emission Spectra

55. The photoelectric effect experiment is performed on strontium metal. When light with  = 389 nm shines on the metal, electrons are ejected at a velocity of 3.97 x 105 m/s. What is the threshold frequency, o, for strontium metal?

Difficulty: Medium

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

56. What is the wavelength of electrons moving at 1.5 x10⁶ m/s (about 0.5% the speed of light)?

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

57. What is the kinetic energy in kJ/mole of electrons with a wavelength of 0.22 nm (the distance between some atoms)?

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

58. What is the wavelength of electrons with kinetic energy 95 kJ/mole?

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

59. At what velocity would an electron need to travel at to have a wavelength of 0.1 nm?

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

60. An electron has velocity of 3 x 10² m s^-1; determine the wavelength and frequency of this electron.

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

61. One wavelength of infrared radiation absorbed by water is 3150 nm. At what velocity will electrons have this wavelength?

Difficulty: Easy

Learning Objective: Describe properties of free electrons and those in atoms or molecules.

Section Reference: 4.4 Properties of Electrons

62. List the possible values of m_l for an electron in a 3p subshell.

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

63. List the possible values for l for an electron in the 4^th principle quantum level.

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

64. List all possible quantum sets for an electron in the 4p quantum level.

Difficulty: Easy

Learning Objective: Write valid sets of quantum numbers for a given set of orbitals.

Section Reference: 4.5 Quantization and Quantum Numbers

65. Atomic orbitals on different atoms can interact with each other, with different results. For now, consider two atoms, A and X. Draw contour pictures of the interaction of the 2s orbital on A with the 2p orbital on X, with the preferred axis of the p orbital (one of the lobes) pointing at the s orbital.

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

66. Atomic orbitals on different atoms can interact with each other, with different results. For now, consider two atoms, A and X. Draw contour pictures of the 2p orbital on A and the 2p orbital on X where the preferred axes are parallel (a side-by-side interaction).

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

67. Which of the following pictures shows the appropriate number of nodes for a 3d orbital?

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

68. Which of the following is a view of the d_xy orbital from the z axis?

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

69. Please define what a node is and how many would be found in a 4p orbital.

Difficulty: Medium

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.6 Shapes of Atomic Orbitals

70. The energy required to convert O₂ molecules to O atoms is 496 kJ/mole. If electromagnetic radiation of 180 nm is absorbed by 1 mole of O₂ molecules, how much kinetic energy will be present in the O atoms?

Difficulty: Medium

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

71. Draw a molecular picture illustrating the decomposition of O₃ to O₂ + O in the stratosphere.

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

72. The bond energy for molecular oxygen, O₂, is 495 kJ/mol; the maximum wavelength of light capable of fragmenting the ozone molecule is 340 nm. What is the difference between the bond energies of O₂ and O_3?

Difficulty: Medium

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

73. The bond energy for molecular oxygen, O₂, is 495 kJ/mol and differs from that of O₃ by 145 kJ mol^-1; what is the maximum wavelength of light capable of fragmenting the ozone molecule?

Difficulty: Hard

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

Feedback: Student must recognize that O₂ bond energy is greater than that of O₃ (O₂ is fragmented in the upper atmosphere, O₃ in lower atmosphere).

74. Explain what properties are needed for a gas to be considered a “greenhouse” gas.

Difficulty: Easy

Learning Objective: Recognize shapes of s, p, d, and f orbitals.

Section Reference: 4.7 Sunlight and the Earth

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