option c nuclear physics, radioactive decay and half life
TRANSCRIPT
http://lawrencekok.blogspot.com
Prepared by Lawrence Kok
Tutorial on Atomic Structure, Particle Physics and Relative Atomic Mass.
Video on scale of universe Excellent Flash on biological cells Excellent Flash on scale of universe
Atomic Structure
Atomic Size radius•Order of magnitude – (10-10 –
10-12)m•Radius Li atom – (1.5 x 10-10)m•Radius nucleus – (1 x 10-14)m
Scale of matter from smallest to largest
1nm – 1 x 10-9
m1pm – 1 x 10-12
m1A - 1 x 10-
10 mRadius Li atom
Radius Nucleus Li atom
Elementary particles making up nucleon (protons + neutrons)
Nucleon - (proton + neutron)Proton – 2 up quark + 1 down quarkNeutron – 2 down quark + 1 up quark
Unit conversion
Video on new particles physics
Atomic Structure
Atomic Size radius•Order of magnitude – (10-10 – 10-
12)m•Radius Li atom – (1.5 x 10-10)m•Radius nucleus – (1 x 10-14)m
1nm – 1 x 10-9
m1pm – 1 x 10-12
m1A - 1 x 10-
10 mRadius Li atom
Radius Nucleus Li atom
Elementary particles making up nucleon (protons + neutrons)
Unit conversion
Structure within atomDiscovery particles with help of Large Hadron Collider
Nucleon - (proton + neutron)Proton – 2 up quark + 1 down quarkNeutron – 2 down quark + 1 up quark
Higgs Boson Discovery Wins Nobel Prize for Physics
Video on Higgs field part 2
Video on Higgs field part 1
Video on timeline discovery Structure within atom
Video on new particles physics
Recent discovery particles from Large Hadron Collider
Higgs boson leftover excitation of particles of Higgs field
Discovery of Higgs boson and Higgs field
Particles interact with Higgs field to produce mass
Video on NOBEL PRIZE 2013 !!!!!!
Discovery timeline to Quantum model Discovery of elementary particles Elementary particles
Video (Minute physics)Video (Ted Talk)Video (RI)Video (Veratasium)
Video on Higgs field
Elementary particlesStructure within atom
Recent discovery particles from Large Hadron Collider
Higgs boson leftover excitation of particles of Higgs field
Discovery of Higgs boson and Higgs field
Particles interact with Higgs field to produce mass
Mass (proton + neutron)- due to interaction bet up quarks/down quarks with gluons (energy fluatution)
Proton -2 up quarks 1 down quark
Neutron -1 up quark 2 down quarks
What is Higgs Boson ?What is Higgs Field ?
Excellent videos –Particles interact with Higgs field create MASS
Nuclear reaction vs Chemical reaction
Nuclear rxnInvolve proton/neutron in nucleus
Decomposition of nucleus into smaller nucleiEnergy released greater
Conservation of charge/atomic mass number
Chemical rxnInvolve outer most electron
Transfer/sharing/loss of electronEnergy released less
Conservation of mass and charge
2Na + CI2 2NaCI
Type radiation
Nature radiation
Symbol
Penetration(mass,m/charge,e)
Ionising power(removing electron)
Alpha Helium nucleus
α Low ratio(high m/e)
High
Beta High energy electron
β Moderate Moderate
Gamma High frequency
electromagnetic
radiation
γ High ratio(small m/e)
Low
Type of radiation
Nuclear equation- decay of nucleus Chemical equation – valence electron
Transfer electrons
Sharing electrons
Nuclear rxn
Alpha DecayLosing an alpha particle – helium nucleusDaughter nuclei lower in proton number
Mass of 4 (2 proton + 2 neutron)+2 charged (only 2 protons) = +2
Decay of uranium, thorium, actinium
Beta DecayLosing beta particle –Electron/positron
Daughter nuclei higher in proton numberNegative charge (-1)
Decay neutron proton + electron
Alpha Decay Beta Decay
Gamma Decay
Gamma decayLosing γ particle - EM radiation high
frequency Daughter nuclei no change in atomic
mass
α β
Unstable nucleus atom Decay by emitting ionizing particles
+
Video on γ decay Video on β decay Video on α decay
Alpha, Beta, Gamma Radiation
Alpha DecayLose alpha particle – helium
nucleusMass He- 4 (2 proton + 2
neutron)+2 charged (2 proton + 2 neutron
+ 0 e)Daughter nuclei lower in proton
number
Beta DecayLose beta particle –Electron/beta β
Negative charge (-1)-1 charged (β / electron)
Daughter nuclei higher in proton number
Gamma decayLose γ particle –EM radiation of high
frequency Daughter nuclei no change in atomic
mass
Nucleus > 84 protonUnstable, radioactive decay
Decay depend ratio neutron/proton
Decay depend ratio neutron/protonNeutron/proton ratio LOW – Proton rich Decay to reduce protonAlpha decay, α (proton number )
Mass number alway Conserved
Decay depend ratio neutron/protonNeutron/proton ratio HIGH – Neutron rich Decay to reduce neutronBeta decay β ( Neutron Proton + electron)Ratio decrease
Decay depend ratio neutron/protonNeutron/proton ratio HIGH /LOWGamma decay γ, is associated along with Alpha and Beta
Radioactive isotopes
Half-life
Uranium 238 4.5 x 109
Carbon-14 5.7 x 103
Radium-226 1.6 x 103
Strontium-90 28 years
Iodine-131 8.1 days
Bismuth-214 19.7 minutes
Polonium-214 1.5 x 10-4
Isotopes
Stable Isotopes Unstable Isotopes
Unstable Isotopes – emit radiation
RADIOISOTOPES
Simulation isotope 12C, 13C, 14C
Radioisotopes Half-life – time taken for conc/amt/number/activity isotope to fall to half of its original value. Half life decay – always constant
Shorter half-life More unstable, decay fast
Long half-life More stable, decay slowly
Emit radiation form unstable isotope
Simulation isotope 1H, 2H, 3H
Video on Half life
Simulation half life C-14/uranuim Half-life
Conc/amt/number/activity
Carbon – 3 Isotopes
Radiocarbon/carbon dating
Half life C-14 = 5730 yrBeta (β/electron ) decay
ConclusionRatio C14/C12 constant is organism alive
Ratio C14/C12 drop organism die
UsesAge dead organic fossil contain Carbon Max age limit 60,000 yrs old.
Carbon -12 Carbon-14Carbon -13
Abundance – 99% (Stable) Abundance – 1% (Stable) Abundance – trace amt (Unstable , radioactive)
How is form?• C-14 produce in stratosphere when neutron hit nitrogen atom to form C-14•C-14 to N-14 by converting neutron proton (proton stay in nucleus), electron emit as β radiation • emit as β ray.
(proton in nucleus – increase proton number)
emit as β ray.
•Ratio C14/C12- constant if alive – TAKE in C14 (C12 constant)•Ratio C14/C12- drop if dead - NOT taking C14. (C12 constant)
How it is form?
Radiocarbon/carbon dating
Half life C-14 = 5730 yrBeta (β/electron ) decay
Carbon -14
Abundance – trace amt (Unstable , radioactive)
How is form?• C-14 produce in stratosphere when neutron hit nitrogen atom to form C-14•C-14 to N-14 by converting neutron proton (proton stay in nucleus), electron emit as β radiation • emit as β ray.
(proton in nucleus – increase proton number)
emit as β ray.
•Ratio C14/C12- constant if alive – TAKE in C14 (C12 constant)•Ratio C14/C12- drop if dead - NOT taking C14. (C12 constant)
Video C-14 Carbon Dating Video C-14 Carbon Dating Video C-14 Half life Carbon Dating
Simulation C-14 (Half life)At 100% (Starting)
Simulation C-14 (Half life)At 50% (Starting)
Video Radiocarbon dating
Click to view simulation
How Radiocarbon dating work?
Video on Radio tracer
Radiocarbon/carbon dating
Half life C-14 = 5730 yr
Carbon -14
Beta (β/electron) decay
Video on C-14 Carbon Dating
Video Radiocarbon dating
How Radiocarbon dating work?
Uses of radioactive isotopes
Radiotherapy/cancer/tumour Tracers/studying metabolic pathways
Cobalt-60
Half life Co-60 = 5.27 yr Half life I-131 = 8 days
How Gamma rays works? How Radio tracer works?
Iodine-131
Sterilization – killing bacteria/germRadiotherapy – kill tumor cells
High energy electromagnetic ray
Gamma γ + β decay
Carbon datingAge of fossil remains
Radio tracerTrace pathway in body
Beta β (90%) and γ (10%) decay
Gamma γ + β decay
Radioactive decay Half life formula
tAA
o
t ][][
ln
tt
t
o
t
eAA
eAA
0][][
][][
2ln
2/1 t
2/15.0 tt
oAA
][. AdecayRate
First order
noAA 5.0
Final conc
Decay constant
Half life
Initial conc
Time
Half-life – time taken for conc/amt/number/activity isotope to fall to half of its original value. Half life decay – always constant
Bismuth-212 half life 1 hr. How long take for 16 g sample to decay, so 1g remain
Time/h Mass left/g
0 16
1 8
2 4
3 2
4 1
Time = 4h
method 1 method 2
hrtime
e
eAA
t
t
o
t
4161][][
693.0
693.01693.0
2ln
2/1
t
Initial conc isotope sample is 1.4 10-6 M .Find half life, if conc left is 1.365 x 10-6M after 2 hr
1
6
6
0126.0
2]104.1[]10365.1[ln
][][
ln
hr
tAA
o
t
hrt
t
550126.02ln
2ln
2/1
2/1
Number Half life
Radioactive decay Half life formula
tAA
o
t ][][
ln
tt
t
o
t
eAA
eAA
0][][
][][
2ln
2/1 t
2/15.0 tt
oAA
][. AdecayRate
First order
noAA 5.0
Final conc
Decay constant
Half life
Initial conc
Time
Number Half life
Rn half life 1620 yrs. Find decay constant, and deduce proportion of sample remain after 100yr
%8.95958.0][][][][][][
100000428.0
o
t
o
t
t
o
t
AA
eAA
eAA
1
2/1
000428.01620693.0
2ln
hr
t
2ln
2/1 t
Rn half life 1622 yrs. Find how long it will take a sample to decay to 10% of its original sample
2ln
2/1 t
1
2/1
000427.01622693.0
2ln
hr
t
yrstime
e
eAA
t
o
t
t
o
t
5392%]100[%]10[][][
000427.0
tAA
o
t ][][
ln
tt
t
o
t
eAA
eAA
0][][
][][
2ln
2/1 t
2/15.0 tt
oAA
][. AdecayRate
First order
noAA 5.0
Final conc
Decay constant
Half life
Initial conc
Time
Piece wood found to have activity of 10 cpm g-1 of carbon .
New wood has count of 15 cpm g-1. Half life C-14 is 5570 yr. Find age of wood.
yrstime
e
eAA
t
o
t
t
o
t
3270]15[]10[][][
000124.0
1
2/1
000124.05570693.0
2ln
yr
t
2ln
2/1 t
Mass sample was measured, and re-measured 120 days later.
56% of original sample remain. Find half life
2ln
2/1 t
dayst
t
14300483.0693.0
2ln
2/1
2/1
100483.0
120%]100[%]56[
ln
][][
ln
day
tAA
o
t
o
t
Sample half life 0f 8hr has activity of 450 unit after 48hr. Find original activity
2/15.0 tt
oAA noAA 5.0
Number Half lifen = 48/8 = 6
unitAA
AA
o
o
tt
o
288465.0450
5.0
848
2/1
unitAA
AA
o
o
no
288465.0450
5.06
Sr -90 half life of 28 yr. Find how much sample left after 280 yr
2/15.0 tt
oAA noAA 5.0
Number Half lifen = 280/28 = 10
%098.0
5.0
5.0
28280
2/1
o
o
tt
o
AAAA
AA
%098.0
5.0
5.010
o
o
no
AAAA
AA
Radioactive decay Half life formula
Number Half life
yrstime
t
tAA
o
t
22460
000121.0604ln
][][
ln
% material decay100% – 0.1% = 99.9% decay
Radioactive decay Half life formula
tAA
o
t ][][
ln
tt
t
o
t
eAA
eAA
0][][
][][
2ln
2/1 t
2/15.0 tt
oAA
][. AdecayRate
First order
noAA 5.0
Final conc
Decay constant
Half life
Initial conc
Time
Piece wood found to have activity of 6 cpm g-1 of carbon .
New wood has count of 15 cpm g-1. Half life C-14 is 5280 yr. Find age of wood.
yrstime
e
eAA
t
o
t
t
o
t
6980]15[]6[][][
000131.0
1
2/1
000131.05280693.0
2ln
yr
t
2ln
2/1 t
Fission product from nuclear shd be isolated for 10 half life. Find fraction radioactive remain after this
time. Deduce % material decay in this time
C-14 in atmosphere produce 60 count hr-1g-1. Sample sea shell found to have 4 count hr-1 g-1. estimate age of shell. Half life C-14 is 5730yr
Pu half life 88yr. Explain why activity sample is constant
over 1 yr. Find % sample remain after 20 yrs.
noAA 5.0
Number Half lifen = 10
%1.0
5.0
5.010
o
o
no
AAAA
AA
remain
2ln
2/1 t
1
2/1
000121.05730693.0
2ln
yr
t
1 yr short compare to half-life, 88 yr, Pu activity doesnt change much
2ln
2/1 t
1
2/1
007877.088693.0
2ln
yr
t
854.0][][][][][][
20007877.0
o
t
o
t
t
o
t
AA
eAA
eAA
= 85.4 %
Number Half life
Acknowledgements
Thanks to source of pictures and video used in this presentationhttp://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/nucnot.htmlhttp://www.m2c3.com/chemistry/VLI/M3_Topic2/M3_Topic2_print.htmlhttp://www.universityneurosurgery.com/index.php?srchttp://www.medwow.com/med/cobalt-linear-accelerator/radon/tr-cobalt-60/42865.model-spechttp://endocrinesurgery.ucla.edu/patient_education_adm_tst_radioactive_iodine_uptake_test.html
Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/
Prepared by Lawrence Kok
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