1. RADIOACTIVITY

2. RADIATION
Radiation are when high energy rays and particles are emitted from radioactive sources
Radioactivity is the release of the high energy particles or rays

3. NUCLEAR SYMBOL Example: K
Chemists represent certain elements using standard atomic notation
The rounded mass number is on the left as a superscript
The atomic number is written on the left as a subscript
Atomic mass
Example: K 39 19
Atomic Number

4. Element
Atomic Number
Rounded Atomic Mass
Nuclear Symbol
Neon
Silicon
Lithium
Bromine
Carbon
Phosphorus
20Ne 10 10 20 14 28
28Si 14 3
7Li 3 7
80Br 35 35 80 12
12C 6 6 15 31
31P 5

5. Whats the difference? Which one is heavier? What is the same?
Group 1
Group 2
Group 3
What is the same?
They are all the same color, but have DIFFERENT masses because there are a DIFFERENT number of blocks!

6. Lets look at this.... Its HYDROGEN!!! Still hydrogen....p+ n p+ p+ p+ n n n
Its HYDROGEN!!!
Still hydrogen....
Still hydrogen????
Because hydrogen’s
atomic number is 1 = 1 proton = 1 electron
These are all hydrogen.... But have different number of protons??

7. ISOTOPES Isotopes are elements with different number of neutrons
If they have a different number of neutrons, they have a different atomic mass!
But, they still have the same number of protons and electrons

8. REPRESENTING ISOTOPES
Nuclear symbols are used to represent isotopes
Mass number = superscript
Atomic number = subscript
Naming isotopes only consists of the “name” – “atomic mass”
Examples:
potassium – 40
carbon - 14

9. MASS NUMBER
Mass number is a number that represents the total number of protons and neutrons in an atom
Mass number:
Mass # = atomic # + # of neutrons
Number of neutrons:
# of neutrons = mass # - atomic #
Number of protons:
# of protons = mass # - # of neutrons

10. Examples of isotopes: 14C 6 14 6 8 Isotope Atomic mass
(neutrons + number)
Atomic number
(protons)
Number of neutrons
(mass – number)
Nuclear symbol
Carbon-14
14C 6 14 6 8
Atomic mass!!!!!

11. Example 2 41K 19 41 19 22 Isotope Atomic mass (neutrons + number)
Atomic number
(protons)
Number of neutrons
(mass – number)
Nuclear symbol
41K 19 41
Potassium -41 19 22
Atomic mass!!!!!

12. Example 3 8Li 3 8 3 5 Isotope Atomic mass (neutrons + number)
Atomic number
(protons)
Number of neutrons
(mass – number)
Nuclear symbol
8Li 3 8
Lithium - 8 3 5

13. ISOTOPE
MASS NUMBER
ATOMIC NUMBER
NUMBER OF NEUTRONS
NUCLEAR SYMBOL
NEON -21 21 10 11
21 Ne
SILICON -30 30 14 26
30 Si
LITHIUM -7 7 3 4
7 Li
Aluminum- 27 27 13
27 Al
Lithium- 6 6
6 Li
Carbon - 14 8
14 C
Magnesium -25 25 12
25 Mg
Fluorine - 19 19 9
19 F

14. CHEMICAL REACTIONS
Chemical reactions occur because atom’s DON’T have a valence shell.
Therefore, they are unstable!!!
So they interact with each other by creating ionic bonds or covalent bonds
But ONLY the electron arrangements (configurations) change, NOT THE PROTONS OR NEUTRONS
... Nuclear reactions are different...

15. RADIOACTIVE DECAY
Radioactive decay is the process in which the unstable nucleus (protons and neutrons) become stable by emitting radiation
By emitting radiation, the atom changes into another element....
Isotopes that are capable of radioactive decay are called radioisotopes

16. ERNEST RUTHERFORD

17. REVIEW NUCLEAR SYMBOL Superscript – up high Subscript – down low
Atomic mass =
Atomic number =
Superscript – up high
Subscript – down low

18. THREE TYPES OF RADIATION
Alpha radiation
Stream of positive alpha particles emitted from the nucleus
Beta Radiation
Stream of negative beta particles emitted from the nucleus
Gamma Radiation
Stream of neutral gamma particles emitted from the nucleus

19. Another Way to Remember
ALPHA
BETA
PROTON
ELECTRON

20. ALPHA RADIATION Symbol:
A stream of alpha particles emitted from the nucleus
Alpha particles are massive and positively charged
Because their massive, they are slow moving and don’t penetrate materials as much
Alpha particles are essentially the same as helium atoms
Symbol:

21. ALPHA RADIATION
An alpha particle is emitted in a process called alpha decay
Then the atomic mass will decrease by 4
The atomic number will decrease by 2
And a new atom will be formed!

22. Another Example: 201Hg  80 197Pt + 78 4He 2 4He 2 231Pa  91 227Ac +89

23. Complete the following:
204Pb 82
227Ac 89
225Ac 89
196Au 79
211Fr 87

24. BETA RADIATION Beta particle is an electron and is negatively charged
They are light weight
Fast moving
Greater penetrating power
SYMBOL
Atomic Mass
Electrical charge

25. n n BETA DECAY p+ e- p+ e- e-
First a neutron changes into a proton and an electron p+ n e-
Then the proton remains in the nucleus while the electron shoots out with a lot of energy p+ n e- e-
The emission of this electron, or beta particle is called beta decay

26. Beta Decay If a beta particle has been emitted
Then the atomic mass will remain the same
But, the atomic number will increase by 1
And a new atom is formed!!
Example:

27. Another Example 0e -1 24Na  11 24 Mg + 12 201Hg  80 201 Tl + 81 0e

28. Complete the following:
201Au 69
14N 7
52Fe 26
6Li 3
24Mg 12
42K 19

29. GAMMA RADIATION
Gamma radiation consists of rays of high energy, short-wavelength radiation.
The gamma particle emitted during gamma decay has no mass and no charge
Greatest penetrating power
SYMBOL

30. Gamma Decay Gamma decay results from the emission of gamma particles
Energy within the nucleus falls from a higher energy state to a lower energy state
It does not change the atomic number or he atomic mass
LOOK FOR *

31. 7.2 HALF LIFE

32. Carbon Dating All organisms on earth contain carbon
Carbon’s isotopes include:
Carbon-12
Carbon-14
When an organism is alive
Carbon -12 = Carbon -14
When an organism dies, carbon-14 atoms start to decrease or decay
Radiocarbon Dating measures the left over carbon-14 to determine age

33. Radiocarbon Dating...

34. Half Life Examples 29 YEARS!!!!
Today you have 100 bucks. After 3 days of spending... You only have 50 dollars left 
How long did it take you to use up HALF of your money?
3 days
Today you have 10 g of strontium-90. After 29 years of decay, there is only 5 g left!
How long did it take for HALF of the sample to decay?
 THAT IS THE HALF LIFE OF YOUR MONEY!!!
29 YEARS!!!!
 THAT IS THE HALF LIFE OF YOUR SAMPLE

35. HALF- LIFE
Half life is the length of time it takes for HALF of the isotope to decay
We compare the rate of radioactive decay by comparing the half life of different isotopes

36. Decay curve
When we graph the rate of radioactivity, it produces a decay curve
The decay curve for all isotopes look the same
ONLY DIFFERENCE is the length of time it takes for the sample to decay

37. CALCULATING HALF LIVES

38. Two Types of Isotopes
The isotope that DECAYS is called the parent isotope
The product AFTER DECAY is called the daughter isotope
Parent Isotope
Daughter Isotope

39. As Parent Isotope decays and decreases
Daughter Isotope increases

40. Parent Isotope + Daughter Isotope = Total Initial mass
A parent isotope has an initial mass of 100 g. Its half life is 5 years. Complete the following table:
Number of Half Lives
Time Elapsed
Parent Isotope
Daughter Isotope
Total Mass 1 2 3 4
100 g
0 years
100 g
0 g
50 g
50 g
100 g
5 years
10 years
25 g
100 g
75g
15 years
12.5 g
87.5 g
100 g
20 years
6.25 g
93.75 g
100g

41. Parent Isotope + Daughter Isotope = Total Initial mass
If this initial mass of the parent isotope is 400 g and it has a half life of 3 years. Complete the following table:
Number of Half Lives
Time Elapsed
Parent Isotope
Daughter Isotope
Total Mass
3 years
400 1
6 years
200 2
9 years
100
300 3
12 years 50
350 4
15 years 25
375

42. The Half Life Triangle of Time
This line is divide
TOTAL TIME
ALWAYS NEED AT LEAST 2 OF THESE VARIABLES
Number of Half Lives
HALF LIFE
This line means multiply

43. Examples
If a sample has a half life of 3 years and it has been decaying for a total of 12 years. What is the number of half lives it has gone through?
TOTAL TIME
HALF LIFE
Number of Half Lives
Number of Half Lives
Total Time
Half Life
12 years
3 years
Number of Half Lives
4 years

44. Examples
If a sample has gone through 5 half lives in a total of 25 years. What is the half life of the sample?
TOTAL TIME
HALF LIFE
Number of Half Lives
Total Time
Half Life
Number of half lives
25 years
5 half lives
Number of Half Lives
5 years

45. If mass is given, draw a half life table!
The initial mass of a sample is 100g. After several half lives, the final mass is 12.5g. How many half lives did the sample go through?
# of Half Life
Mass of parent
100g ÷2 1
50g ÷2 2
25g ÷2 3
12.5g
Number of half Life = 3!!!!

46. Mass Table
How many half lives did a sample go through if the final mass is ¼?
See a fraction???
CONVERT TO PERCENTAGE!!!!!
Final mass=
¼ x 100%
= 25%
Initial Mass=
100%
# of Half Life
Mass of parent
100% ÷2 1
50% ÷2 2
25%
Number of half Life = 2!!!! ÷2

47. Steps to Calculating Half Life!!!
LIST ALL VARIABLES
Initial mass # of Half Life
Final mass Half Lives Total Time
Draw Mass Table
Triangle of Time
Solve for Number of Half Lives
Solve for variable of interest

48. Example 1: Thallium-208 has a half life of 3 minutes
Example 1: Thallium-208 has a half life of 3 minutes. How long does it take for 120 g to decay to 7.50 g?
List Variables:
Initial mass:
Final Mass:
120g
# of
half lives
Half Life:
Total Time:
3 min
????
7.5g
?????
TOTAL TIME
Life
# of
½ life
# Half Life
Mass of parent
Mass of Daughter
120g 0g
# of half life?
4!!!!! 1
60g
60g 2
30g
90g
# of ½ lives
Total time =
½ life x 3
15g
105g
= min X 4
7.5 g
112.5g
= minutes!

49. Example 1: Gold-198 has a half life of 3 days
Example 1: Gold-198 has a half life of 3 days. How much of a 96g sample of gold will be left after 9 days?
List Variables:
Initial mass:
Final Mass:
96g
# of
half lives
Half Life:
Total Time:
3 days
????
????
9 days
TOTAL TIME
Life
# of
½ life
# Half Life
Mass of parent
Mass of Daughter
96g 0g
# of half life?
3!!!! 1
48g
48g 2
24g
72g
Total Time
9 days =
# of ½ life = 3
½ life
3 days
12g
84g =
3!!!!

50. 7.3 NUCLEAR REACTIONS

51. Nuclear Reactions
Nuclear reaction is a process that changes the nucleus by gaining or losing a proton, neutron or electron and gamma rays
A small change in the mass of an tom releases a large amount of energy
Example:
The nuclear fission of 1g of uranium 235 releases the same amount of energy as burning 2 tonnes of coal

52. NUCLEAR FISSION
Nuclear fission is the SPLITTING of the nucleus releasing 2 smaller nuclei, subatomic particles and nuclei

53. Nuclear Fission Massive nucleus 2 smaller nuclei Subatomic particles
Energy

54. Nuclear Fission
Nuclear power plants produce power using nuclear fission
Nuclear fission occurs because the nucleus is heavy with ALOT of protons.
Like charges repel, therefore, these positively charged protons are pushing each other apart
When pushed apart, ENERGY is produce and neutrons are released!

55. Induce Nuclear Fission
Scientists induce a nuclear fission reaction by shooting a neutral, positive or negative particle into the nucleus
However, it is easier to shoot a neutral particle, the neutron to induce a nuclear fission reaction

56. Chain Reaction
After a nuclear reaction starts, it creates a chain reaction and keeps going!
It is this continuous reaction that causes a violent nuclear explosion

57. Nuclear Fusion
Process in which two low mass nuclei join together to make a more massive nucleus.
Occurs at the core of the sun
There is enough pressure and high enough temperatures to force isotopes to collide and fuse

58. Nuclear Fusion

59. Balance Nuclear Fusion Reactions
In a balance nuclear fusion reaction
The combined atomic mass on the left must equal the combined atomic mass on the right
The combined atomic number on the left must equal the combined atomic number on the right!

60. Fusion Reactions H+ H  He + + n + energy2 3 4 1
H H  He n + energy 1 1 2
234 92
141
___ 1
3 n Kr Ba  ____ energy U 92 36 56
___
Remember… what’s on the left of the arrow must EQUAL what’s on the right