1. Unit 17
Radioactivity

2. Atomic mass is the average number of p+ and n found in the nucleus.
All elements have Isotopes. Atoms of the same element with a different number of neutrons found in the nucleus, therefore they have different masses.
Carbon
Chemical symbol: 1 or 2 letters used to represent an element. The 1st letter is always capital. If there is a 2nd letter, it is lower case. C 6
Atomic number is the number of p+ found in the nucleus.

3. Revolving around nucleus
Subatomic Particles
Particle
Mass
Charge
Location in the atom
Proton (p+)
1 amu
1.673 x g +1
1.602 x C
Nucleus
(center of atom)
Neutron (n)
1.675 x g
Electron (e-)
1/1837 amu
9.109 x g -1
x C
Revolving around nucleus

4. Structure of the Atom
Protons & Neutrons

5. Radioactivity
All naturally occurring elements with atomic numbers greater than 83 are radioactive. Uranium is the largest naturally occurring element. Every element above 92 is man-made.
Radioactivity is the uncontrollable decay of an atomic nucleus with the emission of particles and rays, with a lighter element formed.
Radioactive elements can affect photographic plates, ionize gases, and cause physical effects (mutations).

6. half-life takes 4.5 billion years Po  Pb
Half-life is the TIME it takes for ½ of the radioactive atoms to decay.
Different elements take a different amount of time for a half-life to occur.
U  Th
half-life takes 4.5 billion years
Po  Pb
half-life takes 1.6 x 10-4 seconds

7. Radioactive Decay curve
1 line = 5 atoms
Go from 0 to 120 atoms
Radioactive Decay curve
U  Th
Po  Pb
Atoms remaining
1 line = (depends of class data)
Go from 0 rolls to ____ rolls
Time (rolls)

8. For a single element, each half – life is the same amount of time.
Remember that half-life is the period of time required for half of the atoms to go through decay.
For a single element, each half – life is the same amount of time.
So, if it takes 2 minutes for element X to go through one half – life, it takes 4 minutes to go through 2 half – lives.
During each half – life, half of the atoms go through decay.
remaining
1 g st half-life nd rd
decayed
½ g
¼ g
1/8 g
½ g
¾ g
7/8 g

9. Radioactive Emissions
Alpha particle a = Helium nucleus 4 He
easily stopped
Beta particle b = electron e-
moderately difficult to stop
Gamma ray g = pure energy
very difficult to stop 2

10. How a Geiger Counter works
Radioactive emission
a or b
causes ionization of Ar gas, completing circuit, clicks!
How a Geiger Counter works

11. Radioactivity verses Distance
Radioactivity (clicks/min)
1 line = 1 inch
Go from 0 to 12 inches
Distance (in)
1 line = depends on class data
Go from 0 to ____

12. Effectiveness of Various Barriers to Radioactivity
Card board Al Pb
Radioactivity clicks/min
1 line = depends on class data
Go from 0 to ?
1 line = 1 barrier
Go from 0 to 10 barriers
Number of barriers

13. Typical nuclear reactor

15. Drawing of the condition of Chernobyl reactor after the melt down

16. Chernobyl reactor after the melt down

18. Chernobyl reactor core

21. New structure that will enclose the destroyed reactor at Chernobyl.
500 feet long, 840 feet wide, and taller than the Statue of Liberty.

23. Fukushima Daiichi Power Plant
Japan

32. Alpha decay a A X  A-4 N + 4 He
Nuclear Notation
A X
Kinds of Decay
Alpha decay a A X  A-4 N + 4 He
N = new element
Beta decay b A X  A N + e-
N  p+ + e-
Atomic mass
Element symbol z
Atomic number a Z
Z-2 2 b Z
Z+1

34. b a
241Pu 94 a b a a b

36. Calculating half-life of 137Ba56
To calculate the half-life from data, determine the time when exactly half of the radioactive atoms remain.
Radioactivity (clicks/min)
Time (sec)

37. 137 Ba  137 Ba Radioactive Decay of Ba to determine the half - lifeg
137 Ba  Ba Radioactive Decay of Ba to determine the half - life 56 56
Time (s) (clicks/min)
0 25,000
,000
,500
,500
,800
,200
,800
,750
,500
,300
Time (s) (clicks/min)
,400
,700
,800
,000
,200
,600
,050
,650
,200

38. Bikini island

43. Review
a a
1. a. 226Ra  222Rn  218Po
b b
b. 214Bi  214Po  214At Top # = proton + neutron (atomic mass)
Bottom # = protons (atomic number)
2. Protons and neutrons are located in the nucleus, with the electrons located in energy levels around the nucleus.
3. Alpha a particle is a helium nucleus
Beta b particle is an electron
Gamma g ray is pure energy
4. 1/8 pound remaining
7/8 pound decayed
5. A device used to detect radiation by counting the number of emissions per unit of time

44. Nuclear chemistry Crossword
Down
27. Cyclotron
28. Spectrograph
39. Meson
Across
16. Emanations
18. Crystallization
34. Becquerel
40. Rutherford
45. Electroscope

45. Mushroom Cloud from a nuclear bomb.
Size:
468 × 454
Type:
39KB JPG

46. Bikini Atoll is a circle of island with a deep central lagoon
Bikini Atoll is a circle of island with a deep central lagoon.From 1946 to 1958 the US exploded 23 nuclear bombs to analyze what happens. All of the local people were relocated to another atoll before the explosions

48. Light Bright Assignment
1H 2H 3H