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Chemistry 111 > Chapter 2: The Quantum-Mechanical Model of the Atom > Flashcards

Chapter 2: The Quantum-Mechanical Model of the Atom Flashcards

1
Q

Define quantum-mechanical model.

A

A model that explains the behavior of absolutely small particles such as electrons and photons.

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2
Q

Define electromagnetic radiation.

A

A form of energy embodied in oscillating, perpendicular electric and magnetic fields.

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3
Q

How can we characterize a wave?

A

By its amplitude, wavelength, and frequency

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4
Q

Define amplitude.

A

The vertical height of a crest (or depth of a trough) of a wave; a measure of wave intensity.

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5
Q

What does amplitude determine in light?

A

The light’s intensity or brightness - the greater the amplitude, the greater the intensity.

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6
Q

Define wavelength.

A

The distance between adjacent crests of a wave (or any two analogous points).

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7
Q

What does wavelength determine in light?

A

The light’s color

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8
Q

Define frequency.

A

For waves, the number of cycles (or complete wavelengths) that pass through a stationary point in one second. Directly proportional to the speed at which the wave is traveling.

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9
Q

Define hertz (Hz).

A

1 cycle/s; 1/s; s^-1

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10
Q

Formula relationship between frequency and wavelength.

A

c = λ * ν

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11
Q

What is the speed of light (c)?

A

c = 3.00 x 10^8 m/s

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12
Q

Visible light from longest wavelength to shortest wavelength.

A

ROYGBIV

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13
Q

Visible light from lowest frequency to highest frequency.

A

ROYGBIV

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14
Q

Why do objects appear a certain color?

A

Objects reflect the colors in which they appear and absorb most other colors.

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15
Q

Define electromagnetic spectrum.

A

The range of the wavelengths of all possible electromagnetic radiation.

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16
Q

Electromagnetic spectrum from low energy to high energy.

A

Radio, Microwave, Infrared, Visible Light (ROYGBIV), Ultraviolent, X-ray, Gamma-ray

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17
Q

Define interference.

A

The superposition of two or more waves overlapping in space, resulting in either an increase in amplitude (constructive interference) or a decrease in amplitude (destructive interference).

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18
Q

Define constructive interference.

A

The interaction of waves from two sources that align with overlapping crests, resulting in a wave of greater amplitude.

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19
Q

Define destructive interference.

A

The interaction of waves from two sources that are aligned so that the crest of one overlaps the trough of the other, resulting in cancellation.

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20
Q

Define diffraction.

A

The phenomena by which a wave emerging from an aperture spreads out to form a new wave front.

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21
Q

What happens when light passes through two slits separated by a distance comparable to the wavelength of the light?

A

The diffraction of light through the slits results in an interference pattern. Each slit acts as a new wave source, and the two new waves interfere with each other. The resulting pattern is a series of bright and dark lines. At the center, the two waves travel equal distances and interfere constructively. At the point where the difference in distance is one-half on one wavelength, the interference is destructive and a dark line appears. Constructive again at one whole wavelength away.

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22
Q

Define photoelectric effect.

A

The observation that many metals emit electrons when light falls upon the metal.

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23
Q

Define binding energy.

A

Energy with which an electron is bound to the metal.

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24
Q

Define threshold frequency.

A

The frequency at which the energy of a photon exceeds the energy with which an electron is held to the metal, thus ejecting an electron from the metal.

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25
Q

What did Albert Einstein propose for the explanation of the photoelectric effect?

A

Light energy must come in packets, with the amount of energy (E) in a light packet depending on its frequency. The emission of electrons from the metal depends on whether or not a single photon has sufficient energy to dislodge a single electron. For an electron bound to the metal with binding energy Φ, the threshold frequency is reached when the energy of the photon is equal to Φ.

26
Q

Formula Energy relationship to frequency.

A

E = h * ν

27
Q

Define Planck’s constant (h).

A

h = 6.626 x 10^-34 J*s

28
Q

Define photon.

A

(quantum) The smallest possible packet of electromagnetic radiation with an energy = h*v.

29
Q

Formula Energy relationship to wavelength.

A

E = (h*c) / λ

30
Q

Formula threshold frequency.

A

h * v = Φ

31
Q

Formula kinetic energy of ejected electron.

A

KE = (h * v) - Φ

32
Q

Define wave-particle duality of light.

A

Sometimes light appears to behave like a wave, at other times like a particle. The behavior we observe depends on the particular experiment.

33
Q

Define emission spectrum.

A

The range of wavelengths emitted by a particular element; used to identify the element.

34
Q

Why does the emission spectrum of an atom consist of discrete lines?

A

Because the stationary states exist only at specific, fixed energies. The energy of the photon emitted when an electron makes a transition from one stationary state to another is the energy difference between the two stationary states.

35
Q

Relationship between stationary states and energy.

A

Transitions between stationary states that are closer together produce light of lower energy than transitions between stationary states that are farther apart.

36
Q

Define absorption spectrum.

A

A plot of the absorption of light of a sample of matter as a function of wavelength.

37
Q

Define de Broglie relation.

A

The observation that the wavelength of a particle is inversely proportional to its momentum.

38
Q

Formula de Broglie relation.

A

λ = h / (m*v)

39
Q

Define complementary properties.

A

Properties that exclude one another; that is, the more you know about one, the less you know about the other. For example, the wave nature and particle nature of the electron are complementary.

40
Q

Define Heisenberg’s uncertainty principle.

A

The principle stating that due to the wave-particle duality, it is fundamentally impossible to precisely determine both the position and velocity of a particle at a given moment in time.

41
Q

Define deterministic.

A

A characteristic of the classical laws of motion, which imply that present circumstances determine future events.

42
Q

What is a probability distribution map for an electron?

A

It is a statistical map that shows where an electron is likely to be found under a given set of conditions.

43
Q

Define indeterminacy.

A

The principle stating that present circumstances do not necessarily determine future events in the quantum-mechanical realm.

44
Q

Define orbital.

A

A probability distribution map, based on the quantum-mechanical model of the atom, used to describe the likely position of an electron in an atom; also an allowed energy state for an electron.

45
Q

Define quantum number.

A

One of the four interrelated numbers that determine the shape and energy of orbitals, as specified by the solution of the Schrodinger equation.

46
Q

Define principal quantum number (n).

A

An integer that specifies the overall size and energy of an orbital; the higher the quantum number n, the greater the average distance between the electron and the nucleus and the higher its energy. (n = 1, 2, 3, …)

47
Q

Define angular momentum quantum number (l).

A

An integer that determines the shape of an orbital. (l = 0, 1, …, n-1)

48
Q

Define magnetic quantum number (m>l).

A

An integer that specifies the orientation of an orbital. (m>l = -l, …, 0, …, +l)

49
Q

What is the letter designation of an orbital according to l?

A

l=0 : s
l=1 : p
l=2 : d
l=3 : f
l=4 : g
l=5 : h

50
Q

Define spin quantum number (m>s).

A

Specifies the orientation of the spin of the electron. (m>s = -1/2, +1/2)

51
Q

Define electron spin.

A

A fundamental property of electrons; spin can have a value of +1/2 or -1/2.

52
Q

Value of spin up?

A

+1/2

53
Q

Value of spin down?

A

-1/2

54
Q

Define principal level (shell).

A

The group of orbitals with the same value of n.

55
Q

Define sublevel (subshell).

A

Those orbitals in the same principle level with the same value of n and l.

56
Q

Formula number of orbitals in any sublevel.

A

2l + 1

57
Q

Formula number of orbitals in a level.

A

n^2

58
Q

Shape of s orbital (l=0).

A

Spherical, nodes within the sphere at which the probability is 0

59
Q

Shape of p orbital (l=1).

A

Dumbbell, node located at the nucleus. The three p orbitals differ only in their orientation and are orthogonal to each other.

60
Q

Shape of d orbitals (l=2).

A

Four have a clover leaf, one has a dumbbell with a donut around the center.

Chemistry 111 (5 decks)

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