As Physics - Particles (Brampton)

Front 1

Describe the structure of an atom.

Back 1

Front 2

What is the charge of an atom and why?

Back 2

0

The positive and negative charges cancel out since there are the same amount of protons and electrons in an atom.

Front 3

What is mass number (or relative atomic mass) ?

Back 3

The number of protons + the number of neutrons in an atom.

Front 4

What is atomic number?

Back 4

The number of protons in an atom.

Front 5

This is helium. Which number represents:

1) Mass number or Relative atomic mass

2) atomic number?

Back 5

Front 6

What is an isotope?

Back 6

An atom of the same element with a different number of neutrons, but the same number of protons.

Front 7

Give an example of a helium isotope.

(Helium is in the picture)

Back 7

Replacing the mass number with any other number is correct as long as it's positive.

E.g. this is an isotope since it has one more neutron than a normal helium atom.

Front 8

What is the charge(In Coulombs, C) and mass(In kg) of:

A proton

A neutron

An electron

Back 8

Front 9

What are the 2 types of matter/particles?

(Answer is not particles and antiparticles)

Back 9

Hadrons

Leptons

Front 10

When particles interact, what are ALWAYS CONSERVED?

What is conserved sometimes and in what interaction is it conserved?

Back 10

Charge (Q)

Lepton number (L)

Baryon number (B)

:Always conserved

Strangeness (s)

:Only conserved in strong interactions. (Basically interactions involving hadrons, unless the specific interaction is stated)

Front 11

State the names of all the leptons I need to know, their relative charges and their lepton numbers.

(Not including their antiparticles)

Their antiparticles have the same ... But opposite ... ?

Back 11

Their antiparticles have the same mass But opposite everything else. (Charge, lepton number)

Front 12

What kind of particles usually have longer lifetimes and why?

Back 12

Particles containing strange quarks usually have longer lifetimes because strong interactions don't happen often.

Front 13

Check if this interaction can happen.

Back 13

L: 0 → -1 +1

Front 14

Draw what the eightfold way looks like. Label every part of importance.

What do all the particles in the eightfold way have in common?

1) Particles on the same horizontal line have the same...

2) Particles on the same diagonal (left, up) line have the same...

Back 14

They are all mesons.

1) Particles on the same horizontal line have the same strangeness.

2) Particles on the same diagonal (left, up) line have the same charge.

Front 15

Which interaction doesn't affect ALL hadrons?

What is the hadron that isn't affected by this interaction and why?

Back 15

Weak interaction

Protons aren't affected by the weak interaction because they are stable.

Front 16

Briefly state what was done in the Rutherford Scattering.

What 2 conclusions were made and what were the observations that backed up each conclusion?

Back 16

Alpha particles (Helium nucleus particles) were fired at thin gold foil.

Conclusion 1- A large percentage of the atom is empty space since a large amount of alpha particles went straight through the thin gold foil.

Conclusion 2- The (+)charge and mass of the nucleus is very dense and concentrated since a small amount of the alpha particles (about 1/8000) reflected over 90° (due to the repulsion of like charges)

Front 17

What can energy turn into (and what can turn into energy)?

They both have the same answer.

Back 17

Matter

Front 18

Find the specific charge of a proton.

Back 18

Front 19

Proton is also known as a ... Ion?

Back 19

H+ ion (Hydrogen when it's lost its one electron)

Front 20

Define Matter.

Back 20

Particles with mass.

Front 21

Define Specific Charge.

What is the equation for specific charge and what are the units of each component involved?

Back 21

Specific charge- The ratio of a particles charge to it's mass.

Front 22

Find the specific charge of an electron.

Back 22

Front 23

What can you find the specific charges of?

Back 23

Particles, Elements, Compounds etc.

Front 24

What are leptons?

Give an example of a lepton.

Back 24

They are fundamental particles (particles that can't be broken down any further) that dont interact through the strong interaction.

E.g. Electron.

Front 25

What are hadrons?

What are the 2 types of hadrons?

Back 25

Particles made up of quarks that interact through the strong interaction.

Baryons

Mesons.

Front 26

What are Baryons?

Give 2 examples of baryons.

Back 26

They are hadron particles made up of 3 quarks (all quarks or all antiquarks).

E.g. Protons, Neutrons.

Front 27

What are Mesons?

Give 2 examples of mesons.

Back 27

They are hadron particles made up of 2 quarks (1 quark and 1 antiquark).

E.g. Kaon, Pion

Front 28

Antiparticles are the opposite of particles.

What is the same between them?

What is different between them?

Back 28

They have the same mass

But they have the opposite;

Charge

Lepton Number

Baryon Number

Strangeness

Front 29

What is annihilation?

Draw a diagram demonstrating annihilation between an electron and a position.

Back 29

When a particle and its corresponding antiparticle collide, causing their mass to turn into energy as photons.

Front 30

What is Pair Production?

Draw a diagram demonstrating pair production with an electron and a positron

Back 30

When a photon spontaneously turns into a particle and it's corresponding antiparticle.

Front 31

What are the antiparticles for:

A proton

A neutron

An electron?

What are the symbols for each and what are their charges?

Back 31

Front 32

What MUST be conserved in both Annihilation and Pair Production?

Back 32

ENERGY!!!

Front 33

What is the unit for energy?

Back 33

Joules.

Front 34

Define rest energy.

Give the equation for rest energy and what each part of the equation represents.

Back 34

The energy a particle has at rest due to it having mass.

E = mc²

E is rest energy (in J)

m is mass of particle (in kg)

c is speed of light (3 x 10^8)

Front 35

What is the equation for the energy of a photon?

State what each part of the equation means.

Back 35

E = hf

E is photon energy

h is Planck's constant (6.63x10^-34)

f is frequency of the photon.

Front 36

What is the equation used to calculate the energy of the photons produced in annihilation?

State what each part of the equation means.

Explain why this is the equation used to calculate the energy of the photons produced in annihilation.

Back 36

2(photon energy) = 2(rest energy) + 2(kinetic energy)

2(hf) = 2(mc²) + 2(½mv²)

v is velocity (of particles)

m is mass of particles

c is speed of light

h is Planck's constant

f is frequency of photon

This is the equation since 2 particles make 2 photons.

Front 37

What is the equation used to calculate the minimum energy required by a photon to do pair production? State what each part of the equation means.

Why is this the equation for the minimum photon energy required to do pair production?

Back 37

hf↓min = 2(mc²)

f↓min is minimum photon frequency.

This is the minimum energy because kinetic energy of the particles aren't included since there will be no kinetic energy left over.

Front 38

What are the 2 units for energy?

Back 38

Joules

Electron Volts.

Front 39

What is the equation used to calculate the energy of the photon in pair production?

Why is this the equation used to calculate the energy of the photon in pair production?

Back 39

hf = 2(mc²) + 2(½mv²)

This is the equation since 1 photon makes 2 particles.

Front 40

Define Electron Volt.

What is the unit for electron volts?

Back 40

The energy of an electron accelerated through a potential difference of 1V.

Unit is eV

Front 41

What is the conversion for Electron Volts to Joules?

(Remember, Joules are ALWAYS smaller than electron volts)

Back 41

1eV = 1.6 x 10^-19 J

Basically, to go from eV to joules,

x (1.6 x 10^-19)

Front 42

When using an equation that includes energy, do you use joules or electron volts?

Back 42

ALWAYS USE JOULES!

ALWAYS CONVERT ELECTRON VOLTS TO JOULES!

Front 43

Convert 2eV to Joules.

Back 43

2 x (1.6 x 10^-19) = 3.2 x 10^-19 Joules

Front 44

Which particles have a lepton number?

Back 44

Leptons

Front 45

What is the lepton number of an electron? (e^-)

What is the electron number of a positron?(e^+)

Back 45

Electron lepton number: +1

Positron lepton number: -1

Front 46

What is the baryon number of a proton?

What is the baryon number of an antiproton?

Back 46

Proton: +1

Antiproton: -1

Front 47

Which particles have a Baryon number?

Back 47

Baryons.

Front 48

What is the baryon number of a neutron?

What is the baryon number of an antineutron?

Back 48

Neutron: +1

Antineutron: -1

Front 49

What kind of particles are neutrinos and antineutrinos? What are their (particle type) numbers?

What is the symbol for an antineutrino?

What is the symbol for a neutrino?

Back 49

They are leptons.

Front 50

What is the equation for beta minus decay?

Back 50

Front 51

State the names of all the quarks (including antiquarks), their relative charges, their relative masses, and their strangenesses.

(Given in formula sheet so don't stress too much about it)

Back 51

Front 52

Give the relative charges, Relative masses and Quark structures of:

A proton

A neutron

An antiproton

An antineutron

Back 52

Front 53

What is the baryon number of a quark?

What is the baryon number of an antiquark?

Back 53

Quark: B = ⅓

Antiquark: B = -⅓

Front 54

Why do mesons have a baryon number of zero? (B = 0)

Give an example of a meson and demonstrate this.

Back 54

Mesons are made of a quark and antiquark. The quark has a baryon number of ⅓ whilst the antiquarks is -⅓, so they cancel out.

E.g. a Kaon, (K^+), a type of meson, has a quark structure of u(antistrange) so it's charge is 1 and Baryon number is zero.

Front 55

What is the relative mass of ALL quarks, including antiquarks?

Back 55

They all have a relative mass of 1/3

Front 56

Name the 3 forces that act on a nucleus.

Back 56

Electromagnetic force

Gravitational force

Strong nuclear force

Front 57

What kind of particles does the electromagnetic force affect?

Is the electromagnetic force attractive, repulsive or both?

Back 57

Affects charged particles

- can be attractive OR repulsive (both)

Front 58

What kind of particles does the gravitational force affect?

Is gravitational force attractive, repulsive or both?

Back 58

All particles (gravity affects all matter)

It's always attractive

Front 59

Is the strong nuclear force attractive, repulsive or both?

Back 59

Both. It can be attractive or repulsive.

Front 60

What is the purpose of the strong nuclear force in the nucleus?

What would happen if there was no strong nuclear force in the nucleus and why?

Back 60

It keeps the protons and neutrons in the nucleus.

If there was no strong nuclear force, the electromagnetic force would cause the positively charged protons to repell from each other, causing the nucleus to implode.

Front 61

What are the properties of the strong nuclear force?

Back 61

-it's short range

-It's a repulsive force when 2 nucleons are below 0.5fm away from each other

-It's an attractive force when 2 nucleons are between 0.5 and 4fm away from each other

-There if no force when 2 nucleons are above 4fm away from each other.

Front 62

What is the formula for Beta Plus decay?

Back 62

Front 63

Draw the graph that shows how the strong nuclear force acts as the distance between two nucleons (protons or neutrons) varies.

Back 63

(ignore part scribbled in red)

Front 64

What is a Feynman Diagram?

Back 64

A diagram used to show what happens during particle interactions.

Front 65

Draw the Feynman Diagram for a Proton-Proton Collision.

Explain what is happening.

Is this interaction the same for an electon-electron collision?

Back 65

The two protons come close to each other, then they are repelled due to electromagnetic interaction. The virtual photon causes this repulsion.

This interaction is the same for an electron-electron collision, just replace proton for electron.

Front 66

State the 4 types of particle interactions.

Back 66

Strong

Electromagnetic

Weak

Gravitational

Front 67

What is the exchange particle in a strong interaction?

What kind of particles does the strong interaction affect?

Back 67

Gluon

It affects hadrons only.

Front 68

What is the exchange particle in an Electromagnetic interaction?

What kind of particles does the electromagnetic interaction affect?

Back 68

Virtual photon

It affects charged particles.

Front 69

What is the exchange particle in a gravitational interaction?

What kinds of particles does the gravitational interaction affect?

Back 69

Graviton

It affects hadrons and leptons.

Front 70

Draw the Feynman Diagram for a Neutron-neutrino interaction.

Give the equation which represents this interaction.

Explain what is happening.

Back 70

A neutrino interacts with a neutron. A W^- Boson is exchanged, resulting in the production of a proton and a B^- particle (an electron)

Front 71

What is the exchange particle in a weak interaction?

What kinds of particles does the weak interaction affect?

Back 71

W^- and W^+ bosons

It affects Hadrons and leptons.

Front 72

In a particle interaction, what are the 2 things that the exchange particle comserves?

Back 72

It conserves the momentum and the charge.

Front 73

Draw the Feynman diagram for a proton-antineutrino interaction.

Write the equation that represents this interaction.

Explain what is happening.

Back 73

A proton interacts with an anti-neutrino. A W^+ boson is exchanged, resulting in the production of a neutron and a B^+ particle (a positron).

Front 74

Draw the Feynman Diagram for Beta Minus Decay.

Give the equation that represents this interaction.

Explain what is happening.

Back 74

A neutron decays into a proton, causing a W^- boson to be emitted. The W^- boson then decays into a B^- and an anti-neutrino.

Front 75

Draw the Feynman Diagram for Beta Plus Decay.

Write the equation that represents this interaction.

Explain what is happening.

Back 75

A proton decays into a neutron, causing a W^+ boson to be emitted.

The W^+ boson then decays into a B^+ and a neutrino.

Front 76

What are the 4 properties of the W boson exchange particle?

Back 76

1) They have a non-zero rest mass

2) They have a very short range of no more than about 0.001fm

3) They can be positively (W^+) or negatively (W^-) charged.

4) They cause weak interactions to occur.

Front 77

What does the weak interaction do to hadrons and why?

Back 77

It causes them to decay because they are unstable (Except protons)

Front 78

What kinds of interactions affect ALL hadrons?

Back 78

Strong interaction

EM interaction

Gravitational interaction.

Front 79

Draw the Feynman Diagram for a proton-electron collision.

Explain what is happening.

Back 79

An electron is fired at a proton. a W^- boson is exchanged from the electron to the proton to conserve the charge. This results in the production of a neutron and a neutrino.

Front 80

Draw the Feynman Diagram for electron capture.

Explain what is happening.

Back 80

A proton from a proton-rich nucleus interacts with an electron in an inner shell of the atom, just outside the nucleus. This causes a W^+ boson to be exchanged. The proton decays into a neutron and the W^+ boson turns the electron into a neutrino.

Front 81

What kinds of interactions affect ALL Leptons?

Back 81

Weak interaction

Electromagnetic interaction

Gravitational interaction

Front 82

Which interaction are all leptons NOT affected by?

Back 82

Strong interaction.

Front 83

If you are given a particle interaction in exam, what must be conserved for the interaction to happen when:

1) Only Hadrons are involved

2) Only Leptons are involved

3) Both Hadrons and Leptons are involved?

Back 83

1) Charge

Baryon Number

Lepton Number

Strangeness

2) Charge

Baryon Number

Lepton Number

3) same as 1)

Front 84

Check if this interaction can happen.

Back 84

Q is charge

B is baryon number

L is lepton number

S is strangeness (since hadrons are involved)

Front 85

Check if this interaction can happen.

Back 85

Front 86

What is the equation for alpha decay?

Back 86

Front 87

If this element were to undergo alpha decay, give the result.

Back 87

(Don't need to know U goes to Th when it undergoes alpha decay. It will be given in exam. Getting the numbers and the alpha particle right is enough)

Front 88

What is the element that has the highest possible number of protons before becoming unstable?

What is the proton number of this element?

What do elements with proton numbers above this one have in common?

Back 88

Bismuth.

Proton number 83

Elements with proton numbers above 83 are unstable and radioactive.

Front 89

What is alpha radiation stopped by?

What is the penetration ability of alpha radiation?

What is the ionisation ability of alpha radiation?

Give one use of alpha particles.

Back 89

Paper / a few cm of air

Low penetration ability

Highly ionising

Used in smoke detectors

Front 90

What is beta minus radiation stopped by?

What is the penetration ability of beta minus radiation?

What is the ionising ability of beta minus radiation?

Give one use of beta minus radiation and explain how its used in this situation.

Back 90

Stopped by a few mm of aluminium

Medium penetrating

Medium ionising

Used in gauging paper thickness (too thick, not enough B^- gets through, paper must be made thinner and vice versa)

Front 91

What is gamma radiation?

What is the ionising ability of gamma radiation?

What is the penetration ability of gamma radiation?

What is gamma radiation reduced (not stopped) by?

Give one use of gamma radiation.

Back 91

A high energy, high frequency electromagnetic wave.

Low ionising power

Very penetrating

Reduced by lead/concrete

Used in radiotherapy.

Front 92

Give the charges and quark structures of the mesons I need to know. (Not including antiparticles)

How can i find the strangeness of each meson? What about the charge and strangeness of their antiparticles?

Back 92

Pi ^0 can be u(anti u) d(anti d) or s(anti s).

Find the strangeness by adding the strangeness of each quark together. They will be given in the formula sheet

for the antiparticles of these, just use the opposite quark composition and the other characteristics, (E.g. charge), will change.

Front 93

Electrons can undergo diffraction, but under what circumstance?

Back 93

When they are passing through very small gaps about 10^-12 m wide (about the diameter of an atom)

Front 94

Draw a visual demonstration of electron diffraction and explain what is happening.

Back 94

Electrons are fired at metal foil in front of the screen, causing a circular diffraction pattern of concentric circles to form on the screen. (As shown on the right)

Front 95

What does electron-diffraction prove?

Back 95

That particles have wave-particle duality (particles can act like particles and waves)

Front 96

What is the De Broglie wavelength?

What is the equation for the De Broglie wavelength?

Back 96

The wavelength of matter

h/mv or h/p

h is Planck's constant

mv is mass x velocity

p is momentum

Front 97

How can you get a high De Broglie wavelength? (Think of the equation's denominator)

Back 97

Have a very light particle that isn't moving too fast. (Lower denominator, higher de broglie wavelength)

Front 98

If an electron is fired from an electron gun, how can you find the speed of that electron?

(Use V = E/Q

V is voltage

E is energy

Q is charge)

Back 98

V = E/Q

E = VQ

Q is electron charge or e.

E is kinetic energy since the electron is fired

Let E = ½mv²

½mv² = Ve

v = (2eV/m)^½

Front 99

Does light have wave particle duality

(Can light act as a particle and a wave?)

Back 99

Yes

Front 100

What practical proves light can act as a particle?

What practical proves light can act as a wave?

Back 100

Particle - Photoelectric effect

Wave - Young's double slit

Front 101

What is light made up of?

Back 101

Photons

Front 102

What are photons?

What is the equation for one photon?

Back 102

Wave packets of energy.

E = hf

h is Planck's constant (given in formula book)

f is photon frequency

Front 103

What kind of electrons does a metal contain?

If we were to shine light at a metal, what would happen to those electrons? Draw a diagram to show this.

Is this due to the wave Theory of light? If yes or no, why?

Back 103

A metal contains delocalised electrons.

If we were to shine light at a metal, electrons will pop off

No because if this was due to the wave theory of light, then electrons would be liberated from the metal by any frequency of light, as long as the light is bright enough (has a high enough intensity)

Front 104

When electrons are liberated from a metal surface, what do they gain?

Back 104

Thwy gain kinetic energy when they are liberated from a metal surface.

Front 105

Explain the process of measuring the maximum kinetic energy gained by an electron when it's liberated from a specific metal surface.

Draw a diagram to show what the apparatus setup would look like as well.

Back 105

1) Light is shone onto the lower plate

2) The light is absorbed by the electrons on the plate

3) The electrons gain kinetic energy, causing them to jump onto the other side.

4) After this, increase the voltage of the cell until no electrons reach the other side. That is the stopping potential (Vs)

5) Vs = E/Q

Let E equal Ek↓max

Let Q equal electron charge or e

Vs = Ek↓max/e

Ek↓max = Vs x e

Front 106

Why is the kinetic energy needed to liberate an electron from the metal surface known as Ek↓max? (Why is the 'max' there?)

Back 106

The 'max' is put there because we are looking at electrons liberated from the top of the metal surface. The Ek needed to escape the top of the surface is the max Ek the electron can have since they don't lose Ek by travelling through the metal.

Front 107

What is the equation for kinetic energy?

Back 107

Ek = ½mv²

Front 108

What are the two equations that can be used to find the Maximum kinetic energy of an electron liberated from a metal surface?

Back 108

Ek↓max = Vs × e

Vs is stopping potential

e is electron charge

Ek↓max = hf - (work function)

hf is energy given to the electron by a photon

Front 109

What is the work function?

What is the symbol for the work function?

What is the equation used to find the work function?

Back 109

Work function - the minimum energy needed to liberate an electron from a given metal surface.

(work function) = hf↓0

Front 110

Ek↓max = hf - (work function) can be represented by a y = mx + c graph. Draw this graph, label the x and y axis, the x intercept and y intercept.

Back 110

Front 111

What is the Threshold frequency? What is the symbol for threshold frequency?

Back 111

The minimum frequency required by a photon (or the light) to release electron from the metal surface.

Front 112

What were the 3 things that the photoelectric effect proved?

Back 112

1) It proved that light exists as quanta (wave packets of energy known as photons)

2) It proved that a higher intensity of light (more photons) did NOT increase the kinetic energy of the electrons, but increased the number of electrons emitted per second.

3) It proved that Light acts as a particle since 1 photon is absorbed by 1 electron, and 1 to 1 interactions is a trait of particles.

Front 113

Using the

Ek↓max = hf - (work function) equation, how can you increase the kinetic energy of a liberated electron?

Back 113

Increase the light (photon) frequency.

Front 114

Draw a diagram representing excitation.

Explain what is happening.

Back 114

A photon is absorbed by an electron, causing the electron to move up one energy level.

Front 115

Draw a diagram representing de-excitation.

Explain what is happening.

Back 115

An electron moves down one energy level, causing a photon to be emitted.

Front 116

There are two ways of doing ionisation. Draw a diagram that represents each one.

Explain what is happening in each method/diagram.

Back 116

Method 1: A free electron knocks the electron from the atom

Method 2: The electron absorbs a photon with alot of energy, causing it to leave the atom.

Front 117

What are an atom's energy levels measured in?

Back 117

Electron Volts.

Front 118

This is a visual representation of an example set of energy levels. An electron is at the ground state.

1) If a photon of 3eV was fired at the electron, what will happen and why?

2) If a photon of 7eV was fired at the electron, what will happen and why?

3) If an electron wants to move from the 3rd energy level to the ground state, what would happen?

Back 118

1) The photon won't get absorbed since it doesn't have enough energy to move the electron to the next energy level.

2) 7eV, the electron will absorb the photon, gain kinetic energy and move to the 3rd energy level since that is the exact amount of energy needed to move to the 3rd energy level.

3) The electron will move to the ground state and give off a photon of 7eV.

Front 119

If an electron wants to move from an outer energy level to an inner energy level, it will give off a photon.

What will be the energy of the photon?

Express this as an equation.

Back 119

The energy of the photon will be the difference in the energy levels.

hf = E↓2 – E↓1

hf is photon energy

E↓2 is outer energy level

E↓1 is inner energy level

Front 120

If an electron moves from a 7eV energy level to a 5 eV energy level, find the energy of the emitted photon.

Back 120

7eV – 5eV = 2eV

Front 121

If an electron wants to move from the ground state to an outer energy level, it must absorb a photon.

What must the energy of the photon be?

Back 121

The energy of the photon must be the same as the energy level's energy.

Front 122

If an electron wants to move from the ground state to an 8eV energy level, what must the energy of the photon it absorbs be?

Back 122

8eV

Front 123

One equation for photon energy is:

E = hf

What is the other one? And how do you derive it?

Back 123

E = hc/lambda

Derive:

E = hf

f = c/lambda since v = f(lambda)

Sub c/lambda for f.

c is speed of light (3x10^8)

Lambda is wavelength.

Front 124

What are the 2 types of spectrums I need to know?

What is each spectrum used for?

Back 124

Line Absorption spectrum: used to show which wavelengths, or frequencies of light are absorbed by an atom's electron to undergo excitation.

Line Emission spectrum: used to show which wavelengths, or frequencies of light are emitted by an atom's electron when it undergoes de-excitation (moves from an outer energy level to an inner one.)

Front 125

Draw what a line absorption spectrum would look like.

State what each part represents.

What conditions do you need to produce a line absorption spectrum?

Back 125

The coloured parts represent the wavelengths, or frequencies of photons that pass through the atom.

The black lines represent the wavelengths, or frequencies of photons that are absorbed by the atom (which can essentially be used to find the energy levels of the atom using E = hf or hc/lambda since electrons undergoing excitation MUST start from ground state).

If you observe a heated filament or candle whilst it's behind a cool element/gas, you will see a line absorption spectrum.

Front 126

Draw what a line emission spectrum looks like.

State what each part represents.

What 2 things produce a line emission spectrum?

Back 126

The coloured parts represent the wavelengths, or frequencies of the emitted photons.

The black parts represent the wavelengths, or frequencies that emitted photons can't have since none of the differences in energy levels match the energy of the photons with those wavelengths, or frequencies.

Heated elements/gases produce a line emission spectrum.

Front 127

Should you expect to see more lines in an absorption spectrum or emission spectrum, and why?

Back 127

(Top diagram represents excitation, bottom diagram represents de-excitation)

Emission spectrum.

This is because in excitation (absorption spectrum), electrons that absorb photons to move up an energy level MUST ALWAYS start from the ground state.

But in de-excitation (emission spectrum), electrons can move from their current energy level to any one that is below the current one. There are more possibilities.

Front 128

Where do both excitation and de-excitation occur?

Back 128

In flourescent tubes.

Front 129

Explain the process of how a flourescent tube works. Draw a diagram to aid the explanation.

Back 129

1) The flourescent tube contains low pressure mercury gas

2) Electrons are fired from one end to the other

3) The electrons collide with the mercury atoms, causing the mercury atoms to gain energy and the electrons of the mercury atoms to excite and move up an energy level

4) The mercury electrons then de-excite, and emit high-frequency UV photons

5) the UV photons are absorbed by a coating on the outside of the flourescent tube.

6) The electrons in the atoms of the coating excite, then de-excite to a lower energy level, and emit visible light photons.

Front 130

Draw what a continuous emission spectrum would look like.

What 2 things can produce a continuous emission spectrum?

What are these 2 things classified as?

Back 130

Heated filaments or candles can produce a continuous emission spectrum.

They are classified as black bodies.

Front 131

What is a black body?

Back 131

A perfect absorber and emitter of radiation (something that absorbs and emits radiation of all frequencies.)

Front 132

Can all black bodies produce continuous emission spectrums?

Back 132

Yes.

Front 133

Explain how to form a:

Continuous emmission spectrum. Also explain why the continuous emmission spectrum is given off in this situation.

Line Emission Spectrum

Line Absorption Spectrum.

What process allows:

1) A line Emission Spectrum to form? Explain how briefly.

2) A line absorption Spectrum to form? Explain how briefly.

Light from the prism can reflect onto what? (2 things, as examples. Can reflect onto other things as well)

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Continuous emmission spectrum:

Shine a black body (e.g. filament bulb) through a reflective prism. The reflective prism will give off a continuous emmission spectrum. This is because black bodies emit all frequencies and wavelengths of radiation/light, and nothing is absorbing any of the wavelengths of light.

Line Emission Spectrum:

Shine the light from a hot gas (e.g. hot hydrogen) through a reflective prism. The reflective prism will give off a Line emmission spectrum.

1) De-excitation allows a line emmission spectrum to form. This is because in the hot gas, some electrons are given energy by the heat go from outer shells to inner ones, causing them to give off photons.

Line Absorption Spectrum:

Shine the light from a black body (e.g. filament bulb) through a cold gas. Let the light that comes out of the cold gas shine through a reflective prism. The reflective prism will give off a line absorption Spectrum.

2) Excitation allows a line absorption Spectrum to form. This is because the black body gives off light of all wavelengths and frequencies, but some of them are absorbed by the electrons in the cold gas since the photons of those wavelengths will provide them with the amount of energy they need to go from the innest shell to an outer one, Causing gaps when the light reflects off the prism.

Light from the prism can reflect onto a screen, or into someone's eyes/someone's vision.