Chapter 11: Atomic Phenomena Flashcards Preview

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Flashcards in Chapter 11: Atomic Phenomena Deck (30):
1

At absolute zero (0 degrees Kelvin), what occurs:

all random atomic movement stops

2

Blackbody radiators are:

ideal radiators with set light-radiation profiles, dependent on their temperature; ideal radiators are also ideal absorbers and appear black because they absorb all wavelengths of light (when at temperatures lower than their surroundings)

3

The peak wavelength for a blackbody radiator is:

the wavelength at which the object radiates the greatest amount of energy; it is proportional to the blackbody's absolute temperature

4

The intensity of energy being radiated by a blackbody is proportional to:

the fourth power of the body's absolute temperature

5

Blackbody radiation is approximated by:

cavity radiation

6

Equation to determine the peak wavelength emitted by an object at a given temperature (Wien's Displacement Law):

peak)(T) = constant = 2.9 X 10-3 m•K

7

λpeak refers to:

the wavelength at which more energy is emitted than at any other wavelength; it does not refer to the maximum wavelength emitted

8

Equation to determine the total energy emitted by a blackbody (Stefan-Boltzmann Law):

ET = σT4

where σ is a constant, T is the temperature, and ET is the total energy emitted per unit of area

units = W/m2

9

The photoelectric effect is:

the ejection of an electron from the surface of a metal; it occurs in a vacuum when the metal is hit with incident light (a photon) that has a high enough energy to eject the electron

10

The threshold frequency is:

the minimum light frequency necessary to eject an electron from a given metal; depends on the type of metal exposed to radiation

11

Equation to determine the energy of a photon:

E = hf

where h is Planck's constant and f is the frequency of the light. Once you know the frequency, you can find the wavelength using:

λ = c / f

12

The energy of a photon increases with:

increasing frequency

13

Equation to determine the maximum kinetic energy of an electron ejected by an incident photon:

Kmax = hf - W

where W is the work function of the metal in question

W = hft

14

The Work Function is:

the minimum energy required to eject an electron and is related to the threshold frequency of a given metal:

W = hft

15

Relationship between the frequency of the incident photon and the threshold frequency:

if the frequency of the incident photon is less than ft, no electron will be ejected

if the frequency of the incident proton is greater than ft, an electron will be ejected and the maximum kinetic energy will be the difference between hf and hft (the excess energy is converted into KE of the electron)

16

If the photoelectric effect is occuring, what do electrons do?

electrons leaving the surface of the metal will form a current; the magnitude of this current is proportional to the intensity of the incident beam of photons

17

The higher the principal quantum number, the higher the:

energy of an electron

18

The Bohr Model of the Hydrogen Atom is:

an early quantum mechanical model of one-electron systems that proposes a hydrogen atom is a dense nucleus orbited by an electron

19

For an electron to jump from a lower energy orbital to a higher energy orbital, it must:

absorb an amount of energy (hf) exactly equal to the difference between the two energy levels (in the form of a photon of light at the proper frequency)

20

For an electron to jump from a higher energy orbital to a lower energy orbital, it must:

emit an amount of energy (hf) exaclty equal to the difference between the two energy levels (in the form of a photon of light at the proper frequency)

21

Equation to estimate the energy of an electron with a given quantum number (n) in joules:

E = - Rh/n2

where R is Rydberg's constant and n is the quantum level

22

Equation to estimate the energy of an electron with a given quantum number (n) in electron-volts (eV):

En = - 13.6 eV/n2

23

The energy of an electron increases the farther is is from:

the nucleus; the energy gets less negative as it moves farther from the nucleus. Once the energy becomes positive, the electron is no longer bound to the nucleus

24

In Bohr's model, as n2 increases, what happens to the energy of the electron?

it increases

25

Ground state:

the small orbit an electron can be found; the lowest energy level; n = 1

26

An excited state is:

any orbit higher than the electron's ground state, and, thus, has more energy than the ground state

27

Equation to determine the change in energy of an electron due to absorption or emission of a photon:

∆E = Ef - Ei

(both of these values will always be negative; if ∆E is negative, their was an emission of energy and the electron came down states)

units = joules

28

Equation to determine the change in energy of an electron due to absorption or emission of a photon:

hf = |∆E|

units = joules

29

Flourescence is a method by which:

absorbed high frequency light (usually UV) is emitted by a substance as lower frequency light (usually visible light); the electrons return to their ground state in multiple steps, releasing a lower-frequency photon than the absobed photon at each step

30

Equation to find the wavelength of a photon:

λ = c/f

where c = 3 X 108