A Level Quantum

Question 1

What is thermionic emission?

Answer 1

Electrons break off a material due to heating

Question 2

What is an electron volt?

Answer 2

1.6x10^-19 joules

Question 3

What is the threshold frequency?

Answer 3

The minimum frequency of electromagnetic radiation to cause electrons to break off a metal F0

Question 4

What is photon energy?

Answer 4

E =hf
h is Planck’s constant

Question 5

What is Planck’s constant?

Answer 5

6.63x10^-34

Question 6

What is the work function? φ

Answer 6

φ is the minimum amount of energy needed for an electron to break off the metal

Question 7

What is the other equation for photon energy?

Answer 7

hf = φ + 1/2 *mv^2

Question 8

What is a quanta?

Answer 8

A discrete packet of EM radiation

Question 9

How ( in what state ) do electrons exist?

Answer 9

In discrete energy levels given by numbers

Question 10

How can an electron move down energy levels?

Answer 10

By emitting a photon

Question 11

When changing energy levels, what is the photon energy = to?

Answer 11

The difference between energy levels of the electrons

Question 12

How do electrons move up a level? (excited)

Answer 12

By absorbing a photon with an exact energy difference

Question 13

What is the spectrum of light

Answer 13

Continuous

Question 14

What happens when you heat up a gas?

Answer 14

Electrons become excited and move up an energy level

Question 15

How do you get a line emission spectra?

Answer 15

Send white light through a hot gas with a prism you will get a line emission spectra

Question 16

What is a line emission spectra?

Answer 16

Series of bright lines on a blank background.

Question 17

What does each line represent on a line spectra?

Answer 17

The frequency that corresponds to the electron’s energy levels

Question 18

How do you get a line absorption spectra?

Answer 18

White light passes through through a cool gas and then a prism or diffraction grating

Question 19

What happens when electrons are at a low temperature?

Answer 19

The majority return to the ground level

Question 20

What is the relationship between emission and absorption spectra?

Answer 20

The black/coloured lines represent the same thing and would be in the same places

Question 21

What are photons?

Answer 21

Packets of energy being delivered (similar to particles)

Question 22

What is brightness?

Answer 22

A greater quantity of photons, not a greater amount of energy

Question 23

What is the relationship between photon energy and wavelength

Answer 23

E =hf f =c/λ
E =h* c/λ
So λ is indirectly proportional to E

Question 24

What is the stopping voltage?

Answer 24

Vs = (hf- φ)/q

Question 25

What is De Broglie’s wave-particle duality theory?

Answer 25

If light exhibits both wave and particle-like properties, then electrons should too its the wavelength given to particles

Question 26

What is De Broglie’s λ equation?

Answer 26

DB λ = h/ ρ ρ=momentum and h = P constant

Question 27

What is De Broglie’s λ?

Answer 27

The probability of finding a particle at a point and the wavelength given to particles

Question 28

How were electron diffraction patterns discovered?

Answer 28

Voltage used to accelerate the electrons through graphite

Question 29

What is the structure of graphite?

Answer 29

Formed in layers with very small gaps

Question 30

What happens is you decrease the accelerating voltage?

Answer 30

Decreases DB λ so λ is similar to gap length so more diffraction

Question 31

What is a condition for diffraction?

Answer 31

If DB λ has to be similar to the gap length

Question 32

Why do energy levels have negative values?

Answer 32

As energy must be supplied to the system for the electrons to overcome the nucleus’ attractive force

Question 33

What are spectral lines caused by?

Answer 33

Electrons moving to a higher energy level and then back to a lower energy level emitting a photon