radiation radiation. radiation (nuclear decay) first used by marie curie (1899-1903) radiation:...
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Radiation
Radiation (Nuclear Decay)
• First used by Marie Curie (1899-1903)
Radiation: Energy released in the form of particle or electromagnetic waves.
Measured units: rems/millirems
Wilhem Conrad Roentgen Robert Oppenheimer
1903 Radiation 1942 First Chain Reaction
1895 X-rays
Marie Curie Enrico Fermi
1 1945 Nuclear Bomb
History
Radiation is all around Us!! Types of Radiations: Background Radiation/ Natural Sources:
A. Radon gas from rocks and soil (Decay of Uranium)
B. Gamma Rays from ground C. Carbon and Potassium in the body D. Cosmic Rays at ground levels. (High energy particles from outside the Solar system) E. Building materials such as bricks, wood, and stone.
** Radiation increases as altitudes increases.
Man-made Radiation
Sources: A. Medical uses (X-rays, CAT and PET scans and Nuclear energy ) B. Chernobyl (First year) Japan fallout C. Fallout from weapons testing D. Job (Average) E. Nuclear Industry (Waste) F. Others (TV, airplane trips, smoke detectors)
Electromagnetic Spectrum
Non-ionizing vs Ionizing Radiation
Particles
Smaller particles store more energy. They have a greater impact in the body
Dose Response on Tissues
Examples of tissue Sensitivity
Very High White blood cells (bone marrow)Intestinal epitheliumReproductive cells
High Optic lens epitheliumEsophageal epitheliumMucous membranes
Medium Brain – Glial cellsLung, kidney, liver, thyroid, pancreatic epithelium
Low Mature red blood cellsMuscle cellsMature bone and cartilage
Effects of Radiation
Even though we have learned about some harmful effects of radiation,have in mind the following ……..
Americans get about 25 mrems of radiation from food and water we eat each year. This number varies depending what is eaten, where it is grown and how much is eaten. (Bannanas and Brazil nuts contain higher proportions than most food)
Additional amounts of radiation come from man made sources (Mainly medical, dental, construction, and nuclear industry sources)
Americans average between 150-200 mrems of radiation from all sources each year. Places in India and Brazil may have 3,000 mrems yearly. (Radiation levels of 50,000 mrems have not produced any evident ill effects)
Strict safety standards on radiation exposure allow people to work in science, medicine, construction and nuclear power plants.
Activity # 2
**Answer Review Exercise
**Total Annual Millirems (mrems) Dose Worksheet.
Keep in mind the following facts:1. Question #2:
Monterrey’s Elevation is 537m /1,762 ft
2. Question #7: Research miles traveled per year. Example: Mty-Cancun (Round Trip) = 1900miles
3. Research has shown that 50,000 mrems have not produced any evident ill effects
Nuclear Stability
• Nucleus contain Protons and Neutrons.• Contains a strong Electromagnetic force to hold the Protons together.• Nucleus of some elements become unstable releasing energy as the form of radiation.
Radiation can be detected if it:
• Alters a photographic film• Produces an electric charge
in the surrounding air• Can produce fluorescence
(glowing)
Isotopes
• Atoms of an element with the same number of protons and a different number of neutrons.
• Therefore their mass number is also different.
Other Isotopes
Analyzing Isotopes
Write the nuclear symbol for atoms with the following subatomic particles:
A. 8p, 8n, 8e =
B. 17p, 20n, 17e =
C. 47p, 60n, 47e =
Complete the following table :
Analyzing Isotopes SolutionsComplete the following table : • Protons 14 14 14• Neutrons 14 15 16• Electrons 14 14 14• Atomic # 14 14 14• Mass # 28 29 30
Write the nuclear symbol for atoms with the following subatomic particles: 16 37A. A. 8p, 8n, 8e = O B. 17p,20n, 47e =
Cl 8 17
C. 47p, 60n, 47e = 107 Ag 47
• Copper has two isotopes: Cu-63 and Cu-65. Given that the atomic mass of copper from the periodic table is 63.546 amu, which of the two isotopes is most abundant? Explain your answer.
• Analyze the following chart and determine what elements are isotopes of the same element.
Atom A Atom B Atom C Atom D
#P 15 10 15 15
#N 15 10 10 15
#E 15 15 15 10
Mass
Solutions
• Copper has two isotopes: Cu-63 and Cu-65. Given that the atomic mass of copper from the periodic table is 63.546 amu, which of the two isotopes is most abundant? Explain your answer.
The most abundant isotope is Cu-63 because it is closest to the mass of copper on the periodic table.• Analyze the following chart and determine what elements are
isotopes of the same element.Atom A
Atom B Atom C
Atom D
#P 15 10 15 15
#N 15 10 10 15
#E 15 15 15 10
Mass
30 20 25 30
Average Atomic Mass
Check this out!!!http://www.youtube.com/watch?v=xirPkCI1sMA&feature=related
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Calculating Atomic Mass Isotope Mass Abundance
24Mg = 23.99 amu x 78.70/100 = 18.88 amu25Mg = 24.99 amu x 10.13/100 = 2.531 amu26Mg = 25.98 amu x 11.17/100 = 2.902 amu
Atomic mass (average mass) Mg = 24.31 amu
Mg24.31
Basic Chemistry Copyright © 2011 Pearson Education, Inc.
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Gallium is an element found in lasers used in compact disc players. In a sample of gallium, there is 60.11% of 69Ga (atomic mass 68.93) atoms and 39.89% of 71Ga (atomic mass 70.92) atoms.
What is the atomic mass of gallium?
Practice Activity
Basic Chemistry Copyright © 2011 Pearson Education, Inc.
28
69Ga
68.93 amu x 60.11 = 41.43 amu (from 69Ga)
10071Ga
70.92 amu x 39.89 = 28.29 amu (from 71Ga)
100
Atomic mass Ga = 69.72 amu
Solution
31
Ga
69.72
Basic Chemistry Copyright © 2011 Pearson Education, Inc.
Radioactive Decay
=
Half-LifeHalf-life: Time it takes for an isotope to decay to its half amount.
Decay Curve
Drawing a Half-life Bar Graph
Draw a bar graph representing the decay of Barium-139 if you start with a 20 g sample and it must decay to less than 2 g. The half-life of Barium-139 is 80 minutes.Bar Graph
Representationand Percent
Fraction Remaining Mass
Mass in Grams
Time passed (years)
# of Half-life
Drawing a Half-life Bar Graph Solutions
BarGraph Representationand Percent
Fraction Remaining Mass
Mass in Grams
Time passed (years, min)
# of Half-life
12.5%
100
%
50%
25
%
6.25%
Drawing a Half-life Bar Graph Solutions
BarGraph Representationand Percent
Fraction Remaining Mass
2/2 1/2 1/4 1/8 1/16
Mass in Grams
Time passed (years, min)
# of Half-life
12.5%
100
%
50%
25
%
6.25%
Drawing a Half-life Bar Graph Solutions
BarGraph Representationand Percent
Fraction Remaining Mass
2/2 1/2 1/4 1/8 1/16
Mass in Grams
20 g 10 g 5 g 2.5 g 1.25 g
Time passed (years, min)
# of Half-life
12.5%
100
%
50%
25
%
6.25%
Drawing a Half-life Bar Graph Solutions
BarGraph Representationand Percent
Fraction Remaining Mass
2/2 1/2 1/4 1/8 1/16
Mass in Grams
20 g 10 g 5 g 2.5 g 1.25 g
Time passed (years, min)
0 min
80 min
160 min
240 min
320 min
# of Half-life
12.5%
100
%
50%
25
%
6.25%
Drawing a Half-life Bar Graph Solutions
BarGraph Representationand Percent
Fraction Remaining Mass
2/2 1/2 1/4 1/8 1/16
Mass in Grams
20 g 10 g 5 g 2.5 g 1.25 g
Time passed (years, min)
0 min
80 min
160 min
240 min
320 min
# of Half-life
0 1 2 3 4
12.5%
100
%
50%
25
%
6.25%
Harnessing the Nucleus Nuclear Fission Nuclear Fusion
*Chain reaction *High temperatures/Sun & Star*Huge amounts of energy produced *Greater energy produced*Nuclear power plants *Less radioactive waste formed
*Impossible to create artificially
Final Reflection on Radiation……
• * *