Radioactivity One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie

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Howard Gray
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1 1 Nuclear Chemistry

2 Radioactivity 2 One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie ( ). She discovered radioactivity or radioactive decay, the spontaneous disintegration of the nuclei of some elements.

3 Radioactivity or 3 Radioactive Decay The property in which an unstable nucleus gives off particles and/or energy This changes the atomic number (p + ) and forms a new element

4 Radiation 4 The penetrating rays (energy or particles) emitted by a radioactive source

5 Radioisotopes 5 Unstable isotopes that undergo radioactive decay Elements with atomic number 83 and up are radioactive Bismuth and beyond..

6 Nuclear Reactions vs. Normal Chemical Changes 6 Normal Chemical Reactions involve rearranging atoms. The elements don t change. Nuclear reactions involve the nucleus The nucleus opens, and protons and neutrons are rearranged The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together called binding energy

7 Mass Defect 7 Some of the mass can be converted into energy Shown by a very famous equation! E=mc 2 Energy Mass Speed of light

8 8 Types of Radiation Alpha (α) a positively charged helium nucleus Beta (β) an electron Gamma (γ) pure energy; called a ray rather than a particle He e γ

9 9 Other Nuclear Particles Neutron Positron a positive electron Proton usually referred to as hydrogen-1 1 n e 1 H 1 Any other elemental isotope

10 Penetrating Ability 10

11 Balancing Nuclear Reactions In the reactants (starting materials on the left side of an equation) and products (final products on the right side of an equation) 11 Atomic numbers must balance and Mass numbers must balance Use a particle or isotope to fill in the missing protons and neutrons

12 Alpha emission Nuclear Reactions 12 Note that mass number (A) goes down by 4 and atomic number (Z) goes down by 2. Nucleons (nuclear particles protons and neutrons) are rearranged but conserved

13 Nuclear Reactions 13 Alpha emission Try this one: Po 210 undergoes alpha radiation

14 Beta emission Nuclear Reactions 14 Note that mass number is unchanged and atomic number goes up by 1.

15 Nuclear Reactions 15 Beta emission Try this one: Uranium 238 undergoes beta decay

16 Nuclear Fission 16

17 Nuclear Fusion 17

18 Nuclear Reaction 18

19 Nuclear Power Plants 19

20 20 SO YOU SAY YOU WANT TO MELTDOWN YOUR OWN POWER PLANT? HERE S YOUR CHANCE TO PLAY HOMER SIMPSON.

21 21 Nuclear Power Pros and Cons Lot s of energy No green house gases Uses very little fuel Very small chance of massive disaster Potential target for terrorists Nuclear waste

22 22 Accidents can happen The worst nuclear accident in US history occurred on Three Mile Island in PA 1979 The reactor meltdown was caused by several mechanical errors as well as human error creating a coolant leak The reactor that had the melt down is no longer in use. The other reactor is slated to remain in use until 2034 London Calling by The Clash is about this accident

Chernobyl April 1986 23 Chernobyl Nuclear Power Plant Pripyat,

spike, causing several explosions Radiation was picked up several

23 Chernobyl April Chernobyl Nuclear Power Plant Pripyat, Ukraine; April 1986 During a test, the reactor received a power spike, causing several explosions Radiation was picked up several hundred miles away, prompting the Soviet Union to admit the accident, 3

24 Japan Fukushima Power 24 Plant March 2011

25 25 Radiation Detection Film Badges exposure of film measures radiation exposure Geiger Counters- detect radiation through electric pulses in ionized gas Scintillation Counters- measure radiation from substances that emit visible light when energy is absorbed

26 Radiation Detection 26

27 27 Uses of Radiation Radioactive dating can determine the approximate age of an object There are many uses of radiation in the medical field Detect and kill cancerous cells X-Rays Many others Disinfect foods

28 Personal Dose Chart 28

29 Effects of Radiation on the Body 29

30 Half Life 30 Time it takes for ½ a sample to decay No two radioisotopes decay at the same rate Can be as short as a few seconds or take billions of years.

31 31

32 32

33 Half Life 33 Uranium-238 has a half-life of 4.5 billion years. It s stable ending element is lead (Pb)

34 Half Life 34

35 Half Life 35

36 Half Life 36 A 2.5 g sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The halflife of Sr-90 is 28 years. a) How many years will it take for grams of Sr-90 to remain? b) What year will this be?

37 Half Life 37 A 2.5 g sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The halflife of Sr-90 is 28 years. a) How many years will it take for grams of Sr-90 to remain? 56 years b) What year will this be? 2016

38 Half Life 38 The half-life of an isotope is 3.0 years. If 20 mg of this isotope disintigrates over a period of 12 years, how many mg of this isotope will remain?

39 Half Life 39 The half-life of an isotope is 3.0 years. If 20 mg of this isotope disintigrates over a period of 12 years, how many mg of this isotope will remain? 2.5 mg

Nuclear Chemistry. Mass Defect. E=mc 2. Radioactivity. Types of Radiation. Other Nuclear Particles. Nuclear Reactions vs. Normal Chemical Changes

Nuclear Chemistry. Mass Defect. E=mc 2. Radioactivity. Types of Radiation. Other Nuclear Particles. Nuclear Reactions vs. Normal Chemical Changes 1 Nuclear Chemistry Mass Defect 4 Some of the mass can be converted into energy Shown by a very famous equation! E=mc 2 Energy Mass Speed of light Radioactivity 2 Types of Radiation 5 One of the pieces