3.2.2 Quantum

Question 1

What is the Photoelectric effect?

Answer 1

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

Question 2

What is the threshold frequency?

Answer 2

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

Question 3

What is the Work function?

Answer 3

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

Question 4

What is stopping potential?

Answer 4

The potential difference required to stop photoelectron emission from occurring

Question 5

What is the photoelectric equation?

Answer 5

E = h f = ϕ + Ek (max)

Question 6

What is maximum kinetic energy?

Answer 6

The maximum kinetic energy of the
photoelectrons.

Question 7

What is meant by excitation?

Answer 7

Electrons moving up energy levels

Question 8

Electrons can only exist at …..

Answer 8

Discrete energy levels

Question 9

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

Answer 9

Absorbing photons
Colliding with free electrons
Physical factors such as heat

Question 10

What is ionisation?

Answer 10

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

Question 11

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

Answer 11

Ionisation occurs

Question 12

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

Answer 12

Energy, electron, potential

Question 13

1eV = how many joules

Answer 13

1.6 x 10^-19 J

Question 14

What is a fluorescent tube filled with?

Answer 14

Mercury gas, Phosphorus lining

Question 15

How are free electrons in a fluorescent tube accelerated?

Answer 15

A high potential difference is put across the tube

Question 16

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

Answer 16

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

Question 17

How do the Phosphorus atoms emit visible light photons?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

Wavelengths, colours

Question 20

Each element produces ….

Answer 20

A unique set of spectral lines

Question 21

No two elements emit the same set of …..

Answer 21

Spectral lines

Question 22

Elements can be identified by their …..

Answer 22

line spectrum

Question 23

What two types of line spectra are there?

Answer 23

Absorption and emission

Question 24

Spectral lines are evidence for …..

Answer 24

Transitions between discrete energy levels

Question 25

What is the name of the lowest energy level avaliable?

Answer 25

The ground state

Question 26

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

Answer 26

A photon is emitted

Question 27

For emission spectra, what does each transition correspond to?

Answer 27

To a different wavelength

Question 28

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

Answer 28

A discrete energy level

Question 29

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

Answer 29

Certain wavelengths are missing

Question 30

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

Answer 30

A continuous spectrum

Question 31

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

Answer 31

The corresponding emission spectra of the same element

Question 32

What is a difference in energy levels equal to?

Answer 32

A specific photon energy

Question 33

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

Answer 33

Diffraction

Question 34

What is special about diffraction?

Answer 34

It is a characteristic that only waves have

Question 35

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

Answer 35

The photoelectric effect

Question 36

What is the name of light behaving as a packet?

Answer 36

A photon

Question 37

What sort of interaction do photons have?

Answer 37

A one to one interaction

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

Electrons are either emitted or not emitted when exposed to light

Question 41

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

Answer 41

Energy is absorbed instantaneously

Question 42

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

Answer 42

More photonelectrons are released per second

Question 43

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

Answer 43

Less photonelectrons are released per second

Question 44

What properties have electrons shown that they have?

Answer 44

Particle and wave-like properties

Question 45

How can electrons wave-like properties be observed?

Answer 45

Electron diffraction

Question 46

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

Answer 46

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

Question 47

Regarding electron diffraction, what is wavelength inversely proportional to?

Answer 47

Momentum

Question 48

Regarding electron diffraction, if wavelength increases, momentum....

Answer 48

Decreases

Question 49

Regarding electron diffraction, if wavelength decreases, momentum....

Answer 49

Increases

Question 50

What must happen to scientific theories before they become validated?

Answer 50

They must be evaluated and peer reviewed

Question 51

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

Answer 51

Knowledge and understanding