Fission and Fusion

of Atomic Nuclei

I. Nuclear Fission

• Fission - The splitting of the nucleus into fragments (division)

• Uranium-235 is struck by a neutron and forms Ba-141, Kr-92 , and additional neutrons.

Neutron

II. Chain Reaction• Chain reaction – Nucleus captures a

neutron and splits into fragments and produces three neutrons

– Products start a new reaction

• Critical mass– The minimum mass

required to support a self-sustaining chain reaction

III. Nuclear Fusion•Fusion - combining atomic nuclei

to produce a nucleus of greater mass

•Fusion reactions release more energy than fission reactions

•Sun is powered by fusion

euterium

ritium

Question Time

• What is fission?• What is a chain reaction?• What is critical mass?• What is fusion?• Where do we find fusion?

IV. Nuclear Binding Energy

• The energy required to break a nucleus into its individual protons and neutrons

• Energy released in a nuclear reaction is much greater than in chemical reactions

V. Mass Defect•When breaking apart a

nucleus, there is a change in mass called the mass defect.

•The change in mass was converted to energy.

•We know this as E=mc2

VI. Nuclear Reactors• The purpose of nuclear reactors is to keep the

chain reaction going without letting it get out of control

Diablo Canyon

San Onofre

Fukushima, Japan

VII. Nuclear Bombs

Atomic Bomb• Uses fission• Uses enriched uranium-235

or plutonium• Nagasaki and Hiroshima

Hydrogen Bomb• Uses fusion• 1000 time more powerful

than atomic bomb• Uses deuterium 2H and

tritium 3H

Sources• www.pennenergy.com• http://www.californiareport.org• noyonews.net • www.sfgate.com• enformable.com• www.utsandiego.com• activerain.com• thesportdigest.com • www.dailytelegraph.com.au• www.2050publications.com