Radiation Radiation. Radiation (Nuclear Decay) First used by Marie Curie (1899-1903) Radiation: Energy released in the form of particle or electromagnetic

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

http://www.youtube.com/watch?v=xirPkCI1sMA&feature=related




26

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.

27

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


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


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


Mass in Grams

Time passed (years, min)

# of Half-life

12.5%

100

%

50%

25

%

6.25%




2/2 1/2 1/4 1/8 1/16

Mass in Grams


# of Half-life

12.5%

100

%

50%

25

%

6.25%




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


# of Half-life

12.5%

100

%

50%

25

%

6.25%




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


0 min

80 min

160 min

240 min

320 min

# of Half-life

12.5%

100

%

50%

25

%

6.25%




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


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……

• * *

Documents

Radiation Radiation. Radiation (Nuclear Decay) First used by Marie Curie (1899-1903) Radiation: Energy released in the form of particle or electromagnetic