Radioactivity and Nuclear Reactions

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1938- Otto Hahn & Fritz Strassmann split U-235 into smaller nuclei.

1939- Lise Meitner theorized that splitting occurs when the nucleus becomes so unstable that it splits.

The process of splitting a nucleus into smaller nuclei- nuclear fission

Slide 78

What nuclei can split during nuclear fission?

Only large nuclei like U or plutonium can split apart during nuclear fission.

Slide 79

What nuclei can split during nuclear fission?

U-236 is so unstable that it immediately splits into barium & krypton nuclei, several neutrons & a large amount of energy

Slide 80

How are mass & energy related?

Einstein proposed that mass & energy are related & can be changed from one to the other.

Slide 81

How are mass & energy related?

Einstein proposed that mass & energy are related & can be changed from one to the other.

His special theory of relativity says that energy in joules is equal to mass in kg multiplied by the speed of light squared.

Slide 82

How are mass & energy related?

Einstein proposed that mass & energy are related & can be changed from one to the other.

His special theory of relativity says that energy in joules is equal to mass in kg multiplied by the speed of light squared.

Energy (joules) = mass (kg) X speed of light (m/s)2 or E= mc2

Slide 83

What is a chain reaction?

Free neutrons produced by fission can hit other nuclei emitting more neutrons repeating the reaction over and over.

Slide 84

What is a chain reaction?

Free neutrons produced by fission can hit other nuclei emitting more neutrons repeating the reaction over and over.

A series of fission reactions is called a chain reaction.

Slide 85

What is a chain reaction?

Free neutrons produced by fission can hit other nuclei emitting more neutrons repeating the reaction over and over.

A series of fission reactions is called a chain reaction.

An uncontrolled chain reaction releases a huge amount of energy in a short time & requires a critical mass of starting material to produce more reactions.

Slide 86

Nuclear Fusion