Atomic Science

Atomic Science Introductory Physics/ Environmental Science

Canadian Academy

Alpha decay image from h3p://en.wikipedia.org/wiki/Alpha_decay

Unit Ques?ons: “?” Enduring Understandings: •  Nuclear energy can be used to generate electricity

Areas of interac9on:

Human Ingenuity The development of electrical technologies revolu6onised culture

Environments Can we maximise efficiency in order to maximise sustainability?

Criterion Assessment Tasks

C: Unit Test

E: Half-‐life inves?ga?on

A & B: One World

Atomic Science

Draw an Atom! What are the names, sizes, charges and posi?ons of the components? What is the relevance of this to radioac?vity?

The Ob-‐Scertainer How can we really know what we cannot see? Science is a process of observa?ons, hypotheses and tes?ng. 1.  Take 4 or 5 ob-‐scertainers. Play a bit. Predict the shape inside. 2.  Test your hypothesis with careful movements and observa?ons. 3.  Draw your ‘final’ structure. Conclude.

4.  Have an ob-‐scertainer class conference and come up consensus on

the best structure of each of the dishes (there are 12 in total).

Play, predict, draw Modify, conclude

Test

The Ob-‐Scertainer

Atomic Terminology Atom Nuclide Nucleus & Nucleons Atomic Number (Z) Mass Number (A) Neutrons (N) Isotope

Define these terms and then arrange them into a mind-‐map or diagram.

Atomic Terminology Atom: ‘un-‐cu3able’ – the smallest unit of an element Nuclide: an atom specified by an atomic and mass number Nucleus & Nucleons – protons (+) and neutrons (0) in a nucleus Atomic Number (Z) – number of protons in the nucleus, defines the element Mass Number (A) – number of nucleons. Defines the isotope. Neutrons (N) = mass number – atomic number Isotope = atoms of the same element with different mass numbers.

Define these terms and then arrange them into a mind-‐map or diagram.

atomZahl

8 Grid from Desmos the online graphical calculator h3ps://www.abe3ercalculator.com/c

Atomic Number (Z)

Mass N

umbe

r (A)

Protons vs Neutrons Work through the periodic table and plot every figh element. What trends and pa=erns can you iden?fy? Can you suggest a reason for this?

C Atomic Number (Z)

Mass Number (A) 12

6

Neutrons (N) = mass number – atomic number

Radioac9ve Stability


Think about all those posi?vely-‐charged protons next to each other.

What do they want to do? What happens if you add more protons?



Think about all those posi?vely-‐charged protons next to each other. What do they want to do? What happens if you add more protons? This repulsive force is the electromagne9c force. It is not par?cularly strong, but acts over a large distance. So how does the nucleus stay together?

electromagne?c force



Think about all those posi?vely-‐charged protons next to each other. What do they want to do? What happens if you add more protons? This repulsive force is the electromagne9c force. It is not par?cularly strong, but acts over a large distance. So how does the nucleus stay together? The strong force acts between neutrons and protons. It s?cks them together (using gluons – yes, really). The strong force is strong, but acts only over a ?ny distance. As the size of the atom increases, more neutrons are required to keep it stable.

electromagne?c force

strong force

Radioac9ve Decay


When the forces inside the nucleus are unbalanced, decay occurs.

What condi?ons favour these different forms of radioac?ve decay?

-‐

β

α

γ

h3p://phet.colorado.edu/en/simula?on/alpha-‐decay

h3p://phet.colorado.edu/en/simula?on/beta-‐decay

α

β-‐

Gamma decay (γ) is high-‐frequency energy which accompanies other forms of decay.

Radioac9ve Decay Radioac?ve decay is a natural, random change in atomic nuclei that goes on all around us. Radioac?ve materials are going through radioac?ve decay. In this group task, find out about one type of decay and explain to others.

Alpha decay symbol: ( ) Beta-‐ decay symbol: ( ) Gamma Decay symbol: ( γ )

Nucleus is too large and posi?ve.

Nucleus has too many… Nucleus has too much energy ager α or β decay.

___________ is released from the nucleus.

_________ and _______ are released from the nucleus.

A gamma ray is released from the nucleus.

The alpha par?cle is a stable ___________ nucleus (__ protons and ___ neutrons)

The beta-‐par?cle is a fast-‐moving…

The gamma ray is a photon of high-‐frequency energy.

Diagram: Diagram:

Penetra?ng ability: Penetra?ng ability: Penetra?ng ability: Will pass through thin lead.

Image from: h3p://en.wikipedia.org/wiki/Gamma_decay#Gamma_ray_produc?on

Radia9on

Penetra?on image from h3p://en.wikipedia.org/wiki/Radia?on

Radioac?ve decay emits radia?on in different forms.

Radia?on is considered harmful if it is ionizing. This means it interacts with electrons in living things, causing them to become ionised. This results in free radical forma?on, and lots of damage to cells and ?ssues.

When damage is caused to DNA, this can lead to cancers.

Although α radia?on is easily stopped, it may be dangerous if inhaled or ingested.

par?cles

energy

Decay Equa9ons α Decay (proton: neutron ra?o too high) An α par?cle (He) is always lost.

92235U! 2

4He+ ??X

1940K! 2

4He+ ??X

84209Po! 82

205Pb+ ?? ?

24He


Some gamma energy is released, but is not a par6cle (so does figure in our equa6ons)

Mass number decreases by 4. Atomic number decreases by 2.

Decay Equa9ons β-‐ Decay (too many neutrons) Neutron decays into proton. Electron and an?neutrino released.

β-‐ Decay (too many neutrons) A neutron decays into: •  Proton (remains in nucleus) •  β-‐ par?cle (fast electron) •  An?neutrino

Some gamma energy is released, but is not a par6cle (so does figure in our equa6ons)

Alpha decay image from h3p://en.wikipedia.org/wiki/Beta_decay

Decay Equa9ons α Decay (proton: neutron ra?o too high) An α par?cle (He) is always lost.

β-‐ Decay (too many neutrons) Neutron decays into proton. Electron and an?neutrino released.

βplus Decay (too many protons) Proton decays into neutron. Posi?ve electron (positron)and neutrino released.

92235U! 2

4He+ 90231Th

1940K! 2

4He+ 1736Cl

84209Po! 82

205Pb+ 24He

Radioac9ve Decay of Uranium 238 It takes billions of years and many cycles of α decay and β-‐ decay for radioac9ve 238U to become stable 206Pb. Work through the puzzle on the sheet, prac?cing the decay equa?ons and proper nota?on of the isotopes as you go. If you finish: Find out more about ‘half life’. What does it mean?

Decay Lab Carry out this inves6ga6on to learn more about half-‐lives. Assessed for Criterion E: Processing Data.

extra daughters

discard

100 Green beads 100 White beads Radioac?ve green beads decay into white beads. This process is random.

Record the start ?me.

Remove 4 greens from the cup and put in ‘discard’. Replace with white 4 daughter beads. Record “4” as the number of greens removed.

Cover, shake and select 4 at random again. Count and record the greens. Discard and replace.

Repeat un?l 20 random samples have been taken. Record the number of greens each ?me. Record the finish ?me. Total ?me/20 = mean ?me per sample. Record. Reset the simula9on and repeat, this 9me taking 8 beads at random per sample.

1. random 4 sample

2. replace

How could you graph these data and use them to calculate the half

life of the green beads?

green

white


20 cycles of random sampling – 4 at a 9me. Then: Reset the simula9on and repeat, this 9me taking 8 beads at random per sample.

extra daughters

discard

100 Green beads 100 White beads

1. random 4 sample

2. replace

green

white Decreasing

Increasing

Total 6me for each experiment

When you have finished the sampling, save and send to your partner. You’re on your own now. Go to Tools – Protec6on –Unprotect Sheet to be

able to complete the rest of the task.


Plot best-‐fit decay curves (no need for the increases). Adjust the polynomial order so the curves are smooth and realis?c. Remove the labels for the curves which will appear in this legend.



Calcula9ng Half Life For each curve, find as many ‘half intervals’ as possible (e.g. 100-‐>50, 80-‐>40, 60-‐>30). Take a mean of these half intervals. This is an es?mate of the half-‐life of the isotope. What differences do you find between the 4-‐sample and the 8-‐sample? Which es?mate of half life is more reliable? Why?




In the conclusion, work through this scenario. Assume that in the 4-‐sample test, 1 minute represents 100 years. For the material to be considered ‘safe’, it needs to decay to 1/16 of its original amount. Answer the following ques9ons, with jus9fica9on.

•  How long do you need to be concerned about the material? •  How might you store it safely for that long?

Half Life Decay occurs at random – we can’t predict when an individual atoms will decay. However, we can predict the rate at which large quan??es will decay, and this is called half-‐life.

Use this PhET Lab to find out more about half lives of 13C and 238U and how they can be used to es?mate the age of geological materials. Cool.

h3p://phet.colorado.edu/en/simula?on/radioac?ve-‐da?ng-‐game

“The radioac6ve half-‐life for a given radioisotope is the 6me for half the radioac6ve nuclei in any

sample to undergo radioac6ve decay.” Hyperphysics

(h=p://hyperphysics.phy-‐astr.gsu.edu/hbase/nuclear/halfli.html)

Biological Effects of Radia9on Ionising radia?on can damage living ?ssues by causing atoms to become ions, which can in turn become damaging free-‐radicals.

Infographic from: h3p://www.theglobeandmail.com/news/world/asia-‐pacific/how-‐radia?on-‐affects-‐the-‐body/ar?cle1942117/?from=1942081

Biological Effects of Radia9on

Infographic from: h3p://www.theglobeandmail.com/news/world/asia-‐pacific/how-‐radia?on-‐affects-‐the-‐body/ar?cle1942117/?from=1942081

Uses of Nuclear Radia9on Find out more about these uses of radia?on:

•  What type of radia?on? •  How is it used?

Radiocarbon da?ng

Sterilising food & medical equipment Radioac?ve tracers & diagnosis

Radiotherapy: cancer treatment Smoke detectors

29

92238U! 2

4He+ 90234Th

90234Th! "1

0e+ 91234Pa +!

Some Decays. Which are α and which are β-‐?

91234Pa! "1

0e+ 92234U +!

92234U! 2

4He+ 90230Th

90230Th! 2

4He+ 88226Ra

88226Ra! 2

4He+ 86222Rn

86222Rn! 2

4He+ 84218Po

84218Po! 2

4He+ 82214Pb

82214Pb! "1

0e+ 83214Bi +!

83214Bi! "1

0e+ 84214Po +!

84214Po! 2

4He+ 82210Pb

82210Pb! "1

0e+ 83210Bi +!

83210Bi! "1

0e+ 84210Po +!

84210Po! 2

4He+ 82206Pb

91234Pa! "1

0e+ 92234U +!

92238U! 2

4He+ 90234Th 82

214Pb! +10e+ 83

214Bi +!

84214Po! 1

1H + 83213Bi

A. B.

C. D.

88226Ra! 2

4He+ ?? ?

86222Rn87

222Fr

86223Rn80

225U

A. B.

C. D.

90234Th! "1

0e+ ?? ? +! 86

222Rn87222Fr

91234Pa92

238U

A. B.

C. D.

Which is the correct α decay equa?on? Which is the correct β-‐ decay equa?on?

Which product is correct?


817O! 2

4He+ ?? ?

917F

613C

A. B.

C. D.

82210Pb! "1

0e+ ?? ? +! 83

210Bi83211Bi

84214Po80

206Hg

A. B.

C. D.

713C

918F

?? ?! 2

4He+ 92235U

83210Bi84

220Po

94239Pu80

206Hg

A. B.

C. D.




614C

612C

A. B.

C. D.

?? ?! "1

0e+ 56137Ba +! 55

137Cs

83211Bi

A. B.

C. D.

713C

612C

?? ?! 2

4He+ 93237Np

95236Am84

220Po

91233Pa95

241Am

A. B.

C. D.

A. B.

C. D.

83209Bi

84209Bi

83208Bi

58141La

55135Cs 53

131Xe

Check the periodic table. Which are the most common isotopes?

Which nuclide is correct?

Which nuclide is correct?

Where does our energy come from?

Where does our energy come from?

Images from:h3p://en.wikipedia.org/wiki/Sun

1.  Core 2.  Radia?ve zone 3.  Convec?ve zone 4.  Photosphere

5. Chromosphere 6. Corona 7. Sunspot 8. Granules 9. Prominence

Nuclear fusion reac?ons occur in the core of the Sun. How does the Sun’s energy give us the energy we use on Earth?

Nuclear Fusion is how the Sun generates energy!

Images from: h3p://en.wikipedia.org/wiki/Nuclear_fusion

Iden?fy these nuclei. What happens here? What are the products? What is this?

What nuclear force must be overcome in order for fusion t occur? For us to achieve this on Earth takes massive amounts of energy and resources. Fusion is not (yet) a realis?c way of genera?ng energy.

Nuclear Fusion is how the Sun generates energy…

… but we can’t reliably do it here on Earth.

Images from: h3p://en.wikipedia.org/wiki/Nuclear_fusion

Nuclear Fission is what we mean by atomic energy.

Nuclear Fission is how we generate ‘atomic energy’.

Open this PhET Lab on Fission. Describe how a fission reac?on works. •  What is the role of the neutron? •  What happens to the 235U nuclide? •  How is energy released?

h3p://phet.colorado.edu/en/simula?on/nuclear-‐fission

Switch to the Chain Reac9on Set it up in a containment vessel. •  What happens when you add more 235U? •  How does 238U behave? •  Which isotope would you choose to sustain a

chain reac?on, releasing energy?

Switch to the Nuclear Reactor Set it up and get it running! •  What is the effect of removing the control

rods from the reactor? •  How could control rods be used to maintain

safety and control output of energy? •  What are they made of?

Nuclear Fission is how we generate ‘atomic energy’.

Annotate this diagram to describe what is happening in a nuclear fission reac?on. This fission equa9on represents the reac?on: Complete these fission equa?ons:

92235U + 0

1n ! 301n+ 56

141Ba + 3692Kr

Image from: h3p://en.wikipedia.org/wiki/Nuclear_fission

92235U + 0

1n ! 301n+ 37

90Rb + ?? ?

92235U + 0

1n ! 301n+ 55

143Cs + ?? ?

3 neutrons produced

1 neutron in

These neutrons can go on to split other 235U nuclides in a chain reac6on.

energy

Nuclear Energy how do we get electricity from this?

Images from: h3p://en.wikipedia.org/wiki/Nuclear_fission and h3p://en.wikipedia.org/wiki/Pressurized_water_reactor

It takes a lot of binding energy to hold a nucleus together. When we split the atom, we release the daughter par?cles, some neutrons and gamma radia?on. Gamma radia?on is high-‐frequency energy! This energy can be used to heat water, to drive a turbine and power a generator, just like conven?onal electrical genera?on. It all needs magnets to move in rela9on to coils!

Control-‐rods are neutron-‐absorbent materials that can stop or control the

rate of the chain reac?on and therefore control the temperature and

safety of the reactor.

Radioac9ve Waste How do we get rid of it?

3692Kr

Data from: h3p://periodictable.com/Isotopes/056.141/index2.p.full.dm.html

56141Ba

?141 ??

92 ???, 18.3 min

??-‐, 3.9 h

??-‐, 32.5 days

β-‐, 1.8s

??, 4.5s

??, 2.7h

??, 3.5h

The products of nuclear fission are radioac?ve but will decay to stable nuclides. Complete the decay pathways for 92Kr and 141Ba.

?92 ?

?92 ?

?141 ?

?141 ?

Radioac9ve Waste How do we get rid of it?

3692Kr

Data from: h3p://periodictable.com/Isotopes/056.141/index2.p.full.dm.html

56141Ba

57141La37

92Rb

58141Ce

59141 Pr

β-‐, 18.3 min

β-‐, 3.9 h

β-‐, 32.5 days 3892Sr

3992Y

4092Zr

β-‐, 1.8s

β-‐, 4.5s

β-‐, 2.7h

β-‐, 3.5h

The products of nuclear fission are radioac?ve but will decay to stable nuclides. Because nuclear waste is radioac?ve, it needs to be isolated un?l it has decayed to a safe level. This could be underground or in special treatment facili?es. Nuclear reprocessing plants can take the spent fuel rods and extract fissionable materials, such as plutonium, from them. These can be used in other reactors. Next genera?on nuclear reactors will use current nuclear waste as fuel.

42

Can nuclear fission power the planet?

43

92235U + 0

1n ! 301n+ 55

143Cs + 3790Rb

92235U + 0

1n ! 301n+ 56

141Ba + 3692Kr

Fission, Fusion, α-‐Decay or β–Decay?

12H + 1

3H ! 01n+ 2

4He + energy

92238U! 2

4He+ 90234Th

82214Pb! "1

0e+ 83214Bi +!

1940K! 2

4He+ 1736Cl

83214Bi! "1

0e+ 84214Po +!

1. 2. 3. 4. 5. 6. 7.

1532P! "1

0e+ 1632S +!

53131I! "1

0e+ 54131Xe +!

What do you think?

Clipart people from: h3p://www.clker.com/search/krug/1

Ideas based on Concept Cartoons:

h3p://www.conceptcartoons.com

For more resources.

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Atomic Science

Education

forms of decay

decay equa9ons decay

type of decay

onbetadecay alpha decay

alpha decay symbol

gamma decay symbol

beta decay symbol

c force alpha decay