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Physics Aqa > 3.2.2 Quantum > Flashcards

3.2.2 Quantum Flashcards

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1
Q

What is the Photoelectric effect?

A

1.Where photoelectrons are emitted 2.from the surface of a metal
3.due to light of a certain frequency is incident on it

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2
Q

What is the threshold frequency?

A

The minimum frequency of EM radiation required to remove/liberate electrons from the surface of a metal

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3
Q

What is the Work function?

A

The minimum energy required for electrons to be emitted from the surface of a metal

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4
Q

What is stopping potential?

A

The potential difference required to stop photoelectron emission from occurring

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5
Q

What is the photoelectric equation?

A

E = h f = ϕ + Ek (max)

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6
Q

What is maximum kinetic energy?

A

The maximum kinetic energy of the
photoelectrons.

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7
Q

What is meant by excitation?

A

Electrons moving up energy levels

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8
Q

Electrons can only exist at …..

A

Discrete energy levels

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9
Q

What are three ways that electrons can gain energy/ move up energy levels? (3)

A

Absorbing photons
Colliding with free electrons
Physical factors such as heat

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10
Q

What is ionisation?

A

When an electron gains enough energy to be removed from the atom

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11
Q

If the energy of the free electron is greater than the ionisation energy then…..

A

Ionisation occurs

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12
Q

1eV = The ….. gained by one ….. when passing through a ….. difference of 1 volt

A

Energy, electron, potential

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13
Q

1eV = how many joules

A

1.6 x 10^-19 J

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14
Q

What is a fluorescent tube filled with?

A

Mercury gas, Phosphorus lining

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15
Q

How are free electrons in a fluorescent tube accelerated?

A

A high potential difference is put across the tube

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16
Q

How are UV photons emitted by the mercury atoms within a fluorescent tube?

A

The accelerated free electrons collide with and excite mercury atoms which then move down energy levels via emitting a UV photon

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17
Q

How do the Phosphorus atoms emit visible light photons?

A

The phosphorus electrons absorb UV photons, exciting them, then they fall in energy levels via emitting a visible light photon

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18
Q

What are three ways that electrons can move up energy levels? (3)

A

Collisions with other atoms or electrons
Absorbing a photon
Physical sources, such as heat

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19
Q

Excited atoms emit light of certain ….. , which correspond to different …..

A

Wavelengths, colours

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20
Q

Each element produces ….

A

A unique set of spectral lines

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21
Q

No two elements emit the same set of …..

A

Spectral lines

22
Q

Elements can be identified by their …..

A

line spectrum

23
Q

What two types of line spectra are there?

A

Absorption and emission

24
Q

Spectral lines are evidence for …..

A

Transitions between discrete energy levels

25
Q

What is the name of the lowest energy level avaliable?

A

The ground state

26
Q

When electrons transition from a higher to a lower energy level…..

A

A photon is emitted

27
Q

For emission spectra, what does each transition correspond to?

A

To a different wavelength

28
Q

For emission spectra, what is each photons wavelength associated with?

A

A discrete energy level

29
Q

For absorption spectra, what is found when white light is passed through a low pressure and cool gas?

A

Certain wavelengths are missing

30
Q

What does the absorption spectra consist of? (Ignore the missing wavelengths)

A

A continuous spectrum

31
Q

What are the wavelengths that are missing from absorption spectra the same as?

A

The corresponding emission spectra of the same element

32
Q

What is a difference in energy levels equal to?

A

A specific photon energy

33
Q

What is a piece of evidence which shows that light can behave as a wave?

A

Diffraction

34
Q

What is special about diffraction?

A

It is a characteristic that only waves have

35
Q

What is a piece of evidence which shows that light can behave as a particle?

A

The photoelectric effect

36
Q

What is the name of light behaving as a packet?

A

A photon

37
Q

What sort of interaction do photons have?

A

A one to one interaction

38
Q

What does wave theory suggest about the frequency of a wave?

A

That any frequency of light could remove/liberate electrons, if given enough time and exposure

39
Q

What does wave theory suggest about energy absorbed by each photon?

A

That the energy absorbed by each electron will increase gradually with each wave

40
Q

What does the particle theory of light show about electrons emitted when exposed to light?

A

Electrons are either emitted or not emitted when exposed to light

41
Q

What does the particle theory of light show about energy absorbed by each electron?

A

Energy is absorbed instantaneously

42
Q

What does the particle theory of light show when intensity of light is increased?

A

More photonelectrons are released per second

43
Q

What does the particle theory of light show when intensity of light is decreased?

A

Less photonelectrons are released per second

44
Q

What properties have electrons shown that they have?

A

Particle and wave-like properties

45
Q

How can electrons wave-like properties be observed?

A

Electron diffraction

46
Q

Regarding electron diffraction, the amount of diffraction changes due to what?

A

The particle’s momentum change, which is due to the change in wavelength

47
Q

Regarding electron diffraction, what is wavelength inversely proportional to?

A

Momentum

48
Q

Regarding electron diffraction, if wavelength increases, momentum….

A

Decreases

49
Q

Regarding electron diffraction, if wavelength decreases, momentum….

A

Increases

50
Q

What must happen to scientific theories before they become validated?

A

They must be evaluated and peer reviewed

51
Q

….. and …… of the nature of matter has changed over time

A

Knowledge and understanding

Physics Aqa (11 decks)

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